Merge branch 'fbdev/udlfb'
authorPaul Mundt <lethal@linux-sh.org>
Thu, 6 Jan 2011 09:10:09 +0000 (18:10 +0900)
committerPaul Mundt <lethal@linux-sh.org>
Thu, 6 Jan 2011 09:10:09 +0000 (18:10 +0900)
1  2 
drivers/video/Kconfig
drivers/video/Makefile
drivers/video/udlfb.c

diff --combined drivers/video/Kconfig
index fdddf58bdaf511df347695572d0fa1c13d753ee1,37771d0916ef7f84583636473a2d36a7f0db7c18..9f36a29b10b43513df46d120aac360e987a970c8
@@@ -186,14 -186,6 +186,14 @@@ config FB_SYS_FOP
         depends on FB
         default n
  
 +config FB_WMT_GE_ROPS
 +      tristate
 +      depends on FB
 +      default n
 +      ---help---
 +        Include functions for accelerated rectangle filling and area
 +        copying using WonderMedia Graphics Engine operations.
 +
  config FB_DEFERRED_IO
        bool
        depends on FB
@@@ -643,72 -635,6 +643,72 @@@ config FB_BFIN_LQ035Q
          To compile this driver as a module, choose M here: the
          module will be called bfin-lq035q1-fb.
  
 +config FB_BF537_LQ035
 +      tristate "SHARP LQ035 TFT LCD (BF537 STAMP)"
 +      depends on FB && (BF534 || BF536 || BF537) && I2C_BLACKFIN_TWI
 +      select FB_CFB_FILLRECT
 +      select FB_CFB_COPYAREA
 +      select FB_CFB_IMAGEBLIT
 +      select BFIN_GPTIMERS
 +      help
 +        This is the framebuffer device for a SHARP LQ035Q7DB03 TFT LCD
 +        attached to a BF537.
 +
 +        To compile this driver as a module, choose M here: the
 +        module will be called bf537-lq035.
 +
 +config FB_BFIN_7393
 +      tristate "Blackfin ADV7393 Video encoder"
 +      depends on FB && BLACKFIN
 +      select I2C
 +      select FB_CFB_FILLRECT
 +      select FB_CFB_COPYAREA
 +      select FB_CFB_IMAGEBLIT
 +      help
 +        This is the framebuffer device for a ADV7393 video encoder
 +        attached to a Blackfin on the PPI port.
 +        If your Blackfin board has a ADV7393 select Y.
 +
 +        To compile this driver as a module, choose M here: the
 +        module will be called bfin_adv7393fb.
 +
 +choice
 +      prompt  "Video mode support"
 +      depends on FB_BFIN_7393
 +      default NTSC
 +
 +config NTSC
 +      bool 'NTSC 720x480'
 +
 +config PAL
 +      bool 'PAL 720x576'
 +
 +config NTSC_640x480
 +      bool 'NTSC 640x480 (Experimental)'
 +
 +config PAL_640x480
 +      bool 'PAL 640x480 (Experimental)'
 +
 +config NTSC_YCBCR
 +      bool 'NTSC 720x480 YCbCR input'
 +
 +config PAL_YCBCR
 +      bool 'PAL 720x576 YCbCR input'
 +
 +endchoice
 +
 +choice
 +      prompt  "Size of ADV7393 frame buffer memory Single/Double Size"
 +      depends on (FB_BFIN_7393)
 +      default ADV7393_1XMEM
 +
 +config ADV7393_1XMEM
 +      bool 'Single'
 +
 +config ADV7393_2XMEM
 +      bool 'Double'
 +endchoice
 +
  config FB_STI
        tristate "HP STI frame buffer device support"
        depends on FB && PARISC
@@@ -824,14 -750,24 +824,14 @@@ config FB_N41
  config FB_HGA
        tristate "Hercules mono graphics support"
        depends on FB && X86
 -      select FB_CFB_FILLRECT
 -      select FB_CFB_COPYAREA
 -      select FB_CFB_IMAGEBLIT
        help
          Say Y here if you have a Hercules mono graphics card.
  
          To compile this driver as a module, choose M here: the
          module will be called hgafb.
  
 -        As this card technology is 15 years old, most people will answer N
 -        here.
 -
 -config FB_HGA_ACCEL
 -      bool "Hercules mono Acceleration functions (EXPERIMENTAL)"
 -      depends on FB_HGA && EXPERIMENTAL
 -      ---help---
 -      This will compile the Hercules mono graphics with
 -      acceleration functions.
 +        As this card technology is at least 25 years old,
 +        most people will answer N here.
  
  config FB_SGIVW
        tristate "SGI Visual Workstation framebuffer support"
@@@ -1786,24 -1722,6 +1786,24 @@@ config FB_AU120
          various panels and CRTs by passing in kernel cmd line option
          au1200fb:panel=<name>.
  
 +config FB_VT8500
 +      bool "VT8500 LCD Driver"
 +      depends on (FB = y) && ARM && ARCH_VT8500 && VTWM_VERSION_VT8500
 +      select FB_WMT_GE_ROPS
 +      select FB_SYS_IMAGEBLIT
 +      help
 +        This is the framebuffer driver for VIA VT8500 integrated LCD
 +        controller.
 +
 +config FB_WM8505
 +      bool "WM8505 frame buffer support"
 +      depends on (FB = y) && ARM && ARCH_VT8500 && VTWM_VERSION_WM8505
 +      select FB_WMT_GE_ROPS
 +      select FB_SYS_IMAGEBLIT
 +      help
 +        This is the framebuffer driver for WonderMedia WM8505
 +        integrated LCD controller.
 +
  source "drivers/video/geode/Kconfig"
  
  config FB_HIT
@@@ -2116,6 -2034,20 +2116,20 @@@ config FB_SM50
  
          If unsure, say N.
  
+ config FB_UDL
+       tristate "Displaylink USB Framebuffer support"
+       depends on FB && USB
+       select FB_MODE_HELPERS
+       select FB_SYS_FILLRECT
+       select FB_SYS_COPYAREA
+       select FB_SYS_IMAGEBLIT
+       select FB_SYS_FOPS
+       select FB_DEFERRED_IO
+       ---help---
+         This is a kernel framebuffer driver for DisplayLink USB devices.
+         Supports fbdev clients like xf86-video-fbdev, kdrive, fbi, and
+         mplayer -vo fbdev. Supports all USB 2.0 era DisplayLink devices.
+         To compile as a module, choose M here: the module name is udlfb.
  
  config FB_PNX4008_DUM
        tristate "Display Update Module support on Philips PNX4008 board"
diff --combined drivers/video/Makefile
index bdf626419433a4eace336fe8c414df14c94d7acf,03678e3021ab4243c2e516d50236422b40ed5cf9..f9de51c39ad725129817f70cd17512ad4b8d8f8b
@@@ -26,7 -26,6 +26,7 @@@ obj-$(CONFIG_FB_SVGALIB)       += svgal
  obj-$(CONFIG_FB_MACMODES)      += macmodes.o
  obj-$(CONFIG_FB_DDC)           += fb_ddc.o
  obj-$(CONFIG_FB_DEFERRED_IO)   += fb_defio.o
 +obj-$(CONFIG_FB_WMT_GE_ROPS)   += wmt_ge_rops.o
  
  # Hardware specific drivers go first
  obj-$(CONFIG_FB_AMIGA)            += amifb.o c2p_planar.o
@@@ -105,8 -104,6 +105,8 @@@ obj-$(CONFIG_FB_W100)                += w100fb.
  obj-$(CONFIG_FB_TMIO)           += tmiofb.o
  obj-$(CONFIG_FB_AU1100)                 += au1100fb.o
  obj-$(CONFIG_FB_AU1200)                 += au1200fb.o
 +obj-$(CONFIG_FB_VT8500)                 += vt8500lcdfb.o
 +obj-$(CONFIG_FB_WM8505)                 += wm8505fb.o
  obj-$(CONFIG_FB_PMAG_AA)        += pmag-aa-fb.o
  obj-$(CONFIG_FB_PMAG_BA)        += pmag-ba-fb.o
  obj-$(CONFIG_FB_PMAGB_B)        += pmagb-b-fb.o
@@@ -125,6 -122,7 +125,7 @@@ obj-$(CONFIG_FB_PNX4008_DUM_RGB)  += pn
  obj-$(CONFIG_FB_IBM_GXT4500)    += gxt4500.o
  obj-$(CONFIG_FB_PS3)            += ps3fb.o
  obj-$(CONFIG_FB_SM501)            += sm501fb.o
+ obj-$(CONFIG_FB_UDL)            += udlfb.o
  obj-$(CONFIG_FB_XILINX)           += xilinxfb.o
  obj-$(CONFIG_SH_MIPI_DSI)       += sh_mipi_dsi.o
  obj-$(CONFIG_FB_SH_MOBILE_HDMI)         += sh_mobile_hdmi.o
@@@ -144,11 -142,9 +145,11 @@@ obj-$(CONFIG_FB_VESA)             += ve
  obj-$(CONFIG_FB_EFI)              += efifb.o
  obj-$(CONFIG_FB_VGA16)            += vga16fb.o
  obj-$(CONFIG_FB_OF)               += offb.o
 +obj-$(CONFIG_FB_BF537_LQ035)      += bf537-lq035.o
  obj-$(CONFIG_FB_BF54X_LQ043)    += bf54x-lq043fb.o
  obj-$(CONFIG_FB_BFIN_LQ035Q1)     += bfin-lq035q1-fb.o
  obj-$(CONFIG_FB_BFIN_T350MCQB)          += bfin-t350mcqb-fb.o
 +obj-$(CONFIG_FB_BFIN_7393)        += bfin_adv7393fb.o
  obj-$(CONFIG_FB_MX3)            += mx3fb.o
  obj-$(CONFIG_FB_DA8XX)                  += da8xx-fb.o
  
diff --combined drivers/video/udlfb.c
index 0000000000000000000000000000000000000000,74a679ef0f5c1beed87f15c61c52ea3b58a7a781..020589a6bf025ab1b979245d03cd766ff775f6f2
mode 000000,100644..100644
--- /dev/null
@@@ -1,0 -1,1879 +1,1879 @@@
 -      __ATTR(metrics_reset, S_IWUGO, NULL, metrics_reset_store),
+ /*
+  * udlfb.c -- Framebuffer driver for DisplayLink USB controller
+  *
+  * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
+  * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
+  * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
+  *
+  * This file is subject to the terms and conditions of the GNU General Public
+  * License v2. See the file COPYING in the main directory of this archive for
+  * more details.
+  *
+  * Layout is based on skeletonfb by James Simmons and Geert Uytterhoeven,
+  * usb-skeleton by GregKH.
+  *
+  * Device-specific portions based on information from Displaylink, with work
+  * from Florian Echtler, Henrik Bjerregaard Pedersen, and others.
+  */
+ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+ #include <linux/module.h>
+ #include <linux/kernel.h>
+ #include <linux/init.h>
+ #include <linux/usb.h>
+ #include <linux/uaccess.h>
+ #include <linux/mm.h>
+ #include <linux/fb.h>
+ #include <linux/vmalloc.h>
+ #include <linux/slab.h>
+ #include <linux/delay.h>
+ #include <video/udlfb.h>
+ #include "edid.h"
+ static struct fb_fix_screeninfo dlfb_fix = {
+       .id =           "udlfb",
+       .type =         FB_TYPE_PACKED_PIXELS,
+       .visual =       FB_VISUAL_TRUECOLOR,
+       .xpanstep =     0,
+       .ypanstep =     0,
+       .ywrapstep =    0,
+       .accel =        FB_ACCEL_NONE,
+ };
+ static const u32 udlfb_info_flags = FBINFO_DEFAULT | FBINFO_READS_FAST |
+               FBINFO_VIRTFB |
+               FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_FILLRECT |
+               FBINFO_HWACCEL_COPYAREA | FBINFO_MISC_ALWAYS_SETPAR;
+ /*
+  * There are many DisplayLink-based products, all with unique PIDs. We are able
+  * to support all volume ones (circa 2009) with a single driver, so we match
+  * globally on VID. TODO: Probe() needs to detect when we might be running
+  * "future" chips, and bail on those, so a compatible driver can match.
+  */
+ static struct usb_device_id id_table[] = {
+       {.idVendor = 0x17e9, .match_flags = USB_DEVICE_ID_MATCH_VENDOR,},
+       {},
+ };
+ MODULE_DEVICE_TABLE(usb, id_table);
+ /* module options */
+ static int console;   /* Optionally allow fbcon to consume first framebuffer */
+ static int fb_defio;  /* Optionally enable experimental fb_defio mmap support */
+ /* dlfb keeps a list of urbs for efficient bulk transfers */
+ static void dlfb_urb_completion(struct urb *urb);
+ static struct urb *dlfb_get_urb(struct dlfb_data *dev);
+ static int dlfb_submit_urb(struct dlfb_data *dev, struct urb * urb, size_t len);
+ static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size);
+ static void dlfb_free_urb_list(struct dlfb_data *dev);
+ /*
+  * All DisplayLink bulk operations start with 0xAF, followed by specific code
+  * All operations are written to buffers which then later get sent to device
+  */
+ static char *dlfb_set_register(char *buf, u8 reg, u8 val)
+ {
+       *buf++ = 0xAF;
+       *buf++ = 0x20;
+       *buf++ = reg;
+       *buf++ = val;
+       return buf;
+ }
+ static char *dlfb_vidreg_lock(char *buf)
+ {
+       return dlfb_set_register(buf, 0xFF, 0x00);
+ }
+ static char *dlfb_vidreg_unlock(char *buf)
+ {
+       return dlfb_set_register(buf, 0xFF, 0xFF);
+ }
+ /*
+  * On/Off for driving the DisplayLink framebuffer to the display
+  *  0x00 H and V sync on
+  *  0x01 H and V sync off (screen blank but powered)
+  *  0x07 DPMS powerdown (requires modeset to come back)
+  */
+ static char *dlfb_enable_hvsync(char *buf, bool enable)
+ {
+       if (enable)
+               return dlfb_set_register(buf, 0x1F, 0x00);
+       else
+               return dlfb_set_register(buf, 0x1F, 0x07);
+ }
+ static char *dlfb_set_color_depth(char *buf, u8 selection)
+ {
+       return dlfb_set_register(buf, 0x00, selection);
+ }
+ static char *dlfb_set_base16bpp(char *wrptr, u32 base)
+ {
+       /* the base pointer is 16 bits wide, 0x20 is hi byte. */
+       wrptr = dlfb_set_register(wrptr, 0x20, base >> 16);
+       wrptr = dlfb_set_register(wrptr, 0x21, base >> 8);
+       return dlfb_set_register(wrptr, 0x22, base);
+ }
+ /*
+  * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
+  * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
+  */
+ static char *dlfb_set_base8bpp(char *wrptr, u32 base)
+ {
+       wrptr = dlfb_set_register(wrptr, 0x26, base >> 16);
+       wrptr = dlfb_set_register(wrptr, 0x27, base >> 8);
+       return dlfb_set_register(wrptr, 0x28, base);
+ }
+ static char *dlfb_set_register_16(char *wrptr, u8 reg, u16 value)
+ {
+       wrptr = dlfb_set_register(wrptr, reg, value >> 8);
+       return dlfb_set_register(wrptr, reg+1, value);
+ }
+ /*
+  * This is kind of weird because the controller takes some
+  * register values in a different byte order than other registers.
+  */
+ static char *dlfb_set_register_16be(char *wrptr, u8 reg, u16 value)
+ {
+       wrptr = dlfb_set_register(wrptr, reg, value);
+       return dlfb_set_register(wrptr, reg+1, value >> 8);
+ }
+ /*
+  * LFSR is linear feedback shift register. The reason we have this is
+  * because the display controller needs to minimize the clock depth of
+  * various counters used in the display path. So this code reverses the
+  * provided value into the lfsr16 value by counting backwards to get
+  * the value that needs to be set in the hardware comparator to get the
+  * same actual count. This makes sense once you read above a couple of
+  * times and think about it from a hardware perspective.
+  */
+ static u16 dlfb_lfsr16(u16 actual_count)
+ {
+       u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
+       while (actual_count--) {
+               lv =     ((lv << 1) |
+                       (((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
+                       & 0xFFFF;
+       }
+       return (u16) lv;
+ }
+ /*
+  * This does LFSR conversion on the value that is to be written.
+  * See LFSR explanation above for more detail.
+  */
+ static char *dlfb_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
+ {
+       return dlfb_set_register_16(wrptr, reg, dlfb_lfsr16(value));
+ }
+ /*
+  * This takes a standard fbdev screeninfo struct and all of its monitor mode
+  * details and converts them into the DisplayLink equivalent register commands.
+  */
+ static char *dlfb_set_vid_cmds(char *wrptr, struct fb_var_screeninfo *var)
+ {
+       u16 xds, yds;
+       u16 xde, yde;
+       u16 yec;
+       /* x display start */
+       xds = var->left_margin + var->hsync_len;
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x01, xds);
+       /* x display end */
+       xde = xds + var->xres;
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x03, xde);
+       /* y display start */
+       yds = var->upper_margin + var->vsync_len;
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x05, yds);
+       /* y display end */
+       yde = yds + var->yres;
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x07, yde);
+       /* x end count is active + blanking - 1 */
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x09,
+                       xde + var->right_margin - 1);
+       /* libdlo hardcodes hsync start to 1 */
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x0B, 1);
+       /* hsync end is width of sync pulse + 1 */
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x0D, var->hsync_len + 1);
+       /* hpixels is active pixels */
+       wrptr = dlfb_set_register_16(wrptr, 0x0F, var->xres);
+       /* yendcount is vertical active + vertical blanking */
+       yec = var->yres + var->upper_margin + var->lower_margin +
+                       var->vsync_len;
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x11, yec);
+       /* libdlo hardcodes vsync start to 0 */
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x13, 0);
+       /* vsync end is width of vsync pulse */
+       wrptr = dlfb_set_register_lfsr16(wrptr, 0x15, var->vsync_len);
+       /* vpixels is active pixels */
+       wrptr = dlfb_set_register_16(wrptr, 0x17, var->yres);
+       /* convert picoseconds to 5kHz multiple for pclk5k = x * 1E12/5k */
+       wrptr = dlfb_set_register_16be(wrptr, 0x1B,
+                       200*1000*1000/var->pixclock);
+       return wrptr;
+ }
+ /*
+  * This takes a standard fbdev screeninfo struct that was fetched or prepared
+  * and then generates the appropriate command sequence that then drives the
+  * display controller.
+  */
+ static int dlfb_set_video_mode(struct dlfb_data *dev,
+                               struct fb_var_screeninfo *var)
+ {
+       char *buf;
+       char *wrptr;
+       int retval = 0;
+       int writesize;
+       struct urb *urb;
+       if (!atomic_read(&dev->usb_active))
+               return -EPERM;
+       urb = dlfb_get_urb(dev);
+       if (!urb)
+               return -ENOMEM;
+       buf = (char *) urb->transfer_buffer;
+       /*
+       * This first section has to do with setting the base address on the
+       * controller * associated with the display. There are 2 base
+       * pointers, currently, we only * use the 16 bpp segment.
+       */
+       wrptr = dlfb_vidreg_lock(buf);
+       wrptr = dlfb_set_color_depth(wrptr, 0x00);
+       /* set base for 16bpp segment to 0 */
+       wrptr = dlfb_set_base16bpp(wrptr, 0);
+       /* set base for 8bpp segment to end of fb */
+       wrptr = dlfb_set_base8bpp(wrptr, dev->info->fix.smem_len);
+       wrptr = dlfb_set_vid_cmds(wrptr, var);
+       wrptr = dlfb_enable_hvsync(wrptr, true);
+       wrptr = dlfb_vidreg_unlock(wrptr);
+       writesize = wrptr - buf;
+       retval = dlfb_submit_urb(dev, urb, writesize);
+       return retval;
+ }
+ static int dlfb_ops_mmap(struct fb_info *info, struct vm_area_struct *vma)
+ {
+       unsigned long start = vma->vm_start;
+       unsigned long size = vma->vm_end - vma->vm_start;
+       unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
+       unsigned long page, pos;
+       if (offset + size > info->fix.smem_len)
+               return -EINVAL;
+       pos = (unsigned long)info->fix.smem_start + offset;
+       pr_notice("mmap() framebuffer addr:%lu size:%lu\n",
+                 pos, size);
+       while (size > 0) {
+               page = vmalloc_to_pfn((void *)pos);
+               if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
+                       return -EAGAIN;
+               start += PAGE_SIZE;
+               pos += PAGE_SIZE;
+               if (size > PAGE_SIZE)
+                       size -= PAGE_SIZE;
+               else
+                       size = 0;
+       }
+       vma->vm_flags |= VM_RESERVED;   /* avoid to swap out this VMA */
+       return 0;
+ }
+ /*
+  * Trims identical data from front and back of line
+  * Sets new front buffer address and width
+  * And returns byte count of identical pixels
+  * Assumes CPU natural alignment (unsigned long)
+  * for back and front buffer ptrs and width
+  */
+ static int dlfb_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
+ {
+       int j, k;
+       const unsigned long *back = (const unsigned long *) bback;
+       const unsigned long *front = (const unsigned long *) *bfront;
+       const int width = *width_bytes / sizeof(unsigned long);
+       int identical = width;
+       int start = width;
+       int end = width;
+       prefetch((void *) front);
+       prefetch((void *) back);
+       for (j = 0; j < width; j++) {
+               if (back[j] != front[j]) {
+                       start = j;
+                       break;
+               }
+       }
+       for (k = width - 1; k > j; k--) {
+               if (back[k] != front[k]) {
+                       end = k+1;
+                       break;
+               }
+       }
+       identical = start + (width - end);
+       *bfront = (u8 *) &front[start];
+       *width_bytes = (end - start) * sizeof(unsigned long);
+       return identical * sizeof(unsigned long);
+ }
+ /*
+  * Render a command stream for an encoded horizontal line segment of pixels.
+  *
+  * A command buffer holds several commands.
+  * It always begins with a fresh command header
+  * (the protocol doesn't require this, but we enforce it to allow
+  * multiple buffers to be potentially encoded and sent in parallel).
+  * A single command encodes one contiguous horizontal line of pixels
+  *
+  * The function relies on the client to do all allocation, so that
+  * rendering can be done directly to output buffers (e.g. USB URBs).
+  * The function fills the supplied command buffer, providing information
+  * on where it left off, so the client may call in again with additional
+  * buffers if the line will take several buffers to complete.
+  *
+  * A single command can transmit a maximum of 256 pixels,
+  * regardless of the compression ratio (protocol design limit).
+  * To the hardware, 0 for a size byte means 256
+  *
+  * Rather than 256 pixel commands which are either rl or raw encoded,
+  * the rlx command simply assumes alternating raw and rl spans within one cmd.
+  * This has a slightly larger header overhead, but produces more even results.
+  * It also processes all data (read and write) in a single pass.
+  * Performance benchmarks of common cases show it having just slightly better
+  * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
+  * But for very rl friendly data, will compress not quite as well.
+  */
+ static void dlfb_compress_hline(
+       const uint16_t **pixel_start_ptr,
+       const uint16_t *const pixel_end,
+       uint32_t *device_address_ptr,
+       uint8_t **command_buffer_ptr,
+       const uint8_t *const cmd_buffer_end)
+ {
+       const uint16_t *pixel = *pixel_start_ptr;
+       uint32_t dev_addr  = *device_address_ptr;
+       uint8_t *cmd = *command_buffer_ptr;
+       const int bpp = 2;
+       while ((pixel_end > pixel) &&
+              (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
+               uint8_t *raw_pixels_count_byte = 0;
+               uint8_t *cmd_pixels_count_byte = 0;
+               const uint16_t *raw_pixel_start = 0;
+               const uint16_t *cmd_pixel_start, *cmd_pixel_end = 0;
+               prefetchw((void *) cmd); /* pull in one cache line at least */
+               *cmd++ = 0xAF;
+               *cmd++ = 0x6B;
+               *cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
+               *cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
+               *cmd++ = (uint8_t) ((dev_addr) & 0xFF);
+               cmd_pixels_count_byte = cmd++; /*  we'll know this later */
+               cmd_pixel_start = pixel;
+               raw_pixels_count_byte = cmd++; /*  we'll know this later */
+               raw_pixel_start = pixel;
+               cmd_pixel_end = pixel + min(MAX_CMD_PIXELS + 1,
+                       min((int)(pixel_end - pixel),
+                           (int)(cmd_buffer_end - cmd) / bpp));
+               prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);
+               while (pixel < cmd_pixel_end) {
+                       const uint16_t * const repeating_pixel = pixel;
+                       *(uint16_t *)cmd = cpu_to_be16p(pixel);
+                       cmd += 2;
+                       pixel++;
+                       if (unlikely((pixel < cmd_pixel_end) &&
+                                    (*pixel == *repeating_pixel))) {
+                               /* go back and fill in raw pixel count */
+                               *raw_pixels_count_byte = ((repeating_pixel -
+                                               raw_pixel_start) + 1) & 0xFF;
+                               while ((pixel < cmd_pixel_end)
+                                      && (*pixel == *repeating_pixel)) {
+                                       pixel++;
+                               }
+                               /* immediately after raw data is repeat byte */
+                               *cmd++ = ((pixel - repeating_pixel) - 1) & 0xFF;
+                               /* Then start another raw pixel span */
+                               raw_pixel_start = pixel;
+                               raw_pixels_count_byte = cmd++;
+                       }
+               }
+               if (pixel > raw_pixel_start) {
+                       /* finalize last RAW span */
+                       *raw_pixels_count_byte = (pixel-raw_pixel_start) & 0xFF;
+               }
+               *cmd_pixels_count_byte = (pixel - cmd_pixel_start) & 0xFF;
+               dev_addr += (pixel - cmd_pixel_start) * bpp;
+       }
+       if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
+               /* Fill leftover bytes with no-ops */
+               if (cmd_buffer_end > cmd)
+                       memset(cmd, 0xAF, cmd_buffer_end - cmd);
+               cmd = (uint8_t *) cmd_buffer_end;
+       }
+       *command_buffer_ptr = cmd;
+       *pixel_start_ptr = pixel;
+       *device_address_ptr = dev_addr;
+       return;
+ }
+ /*
+  * There are 3 copies of every pixel: The front buffer that the fbdev
+  * client renders to, the actual framebuffer across the USB bus in hardware
+  * (that we can only write to, slowly, and can never read), and (optionally)
+  * our shadow copy that tracks what's been sent to that hardware buffer.
+  */
+ static int dlfb_render_hline(struct dlfb_data *dev, struct urb **urb_ptr,
+                             const char *front, char **urb_buf_ptr,
+                             u32 byte_offset, u32 byte_width,
+                             int *ident_ptr, int *sent_ptr)
+ {
+       const u8 *line_start, *line_end, *next_pixel;
+       u32 dev_addr = dev->base16 + byte_offset;
+       struct urb *urb = *urb_ptr;
+       u8 *cmd = *urb_buf_ptr;
+       u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
+       line_start = (u8 *) (front + byte_offset);
+       next_pixel = line_start;
+       line_end = next_pixel + byte_width;
+       if (dev->backing_buffer) {
+               int offset;
+               const u8 *back_start = (u8 *) (dev->backing_buffer
+                                               + byte_offset);
+               *ident_ptr += dlfb_trim_hline(back_start, &next_pixel,
+                       &byte_width);
+               offset = next_pixel - line_start;
+               line_end = next_pixel + byte_width;
+               dev_addr += offset;
+               back_start += offset;
+               line_start += offset;
+               memcpy((char *)back_start, (char *) line_start,
+                      byte_width);
+       }
+       while (next_pixel < line_end) {
+               dlfb_compress_hline((const uint16_t **) &next_pixel,
+                            (const uint16_t *) line_end, &dev_addr,
+                       (u8 **) &cmd, (u8 *) cmd_end);
+               if (cmd >= cmd_end) {
+                       int len = cmd - (u8 *) urb->transfer_buffer;
+                       if (dlfb_submit_urb(dev, urb, len))
+                               return 1; /* lost pixels is set */
+                       *sent_ptr += len;
+                       urb = dlfb_get_urb(dev);
+                       if (!urb)
+                               return 1; /* lost_pixels is set */
+                       *urb_ptr = urb;
+                       cmd = urb->transfer_buffer;
+                       cmd_end = &cmd[urb->transfer_buffer_length];
+               }
+       }
+       *urb_buf_ptr = cmd;
+       return 0;
+ }
+ int dlfb_handle_damage(struct dlfb_data *dev, int x, int y,
+              int width, int height, char *data)
+ {
+       int i, ret;
+       char *cmd;
+       cycles_t start_cycles, end_cycles;
+       int bytes_sent = 0;
+       int bytes_identical = 0;
+       struct urb *urb;
+       int aligned_x;
+       start_cycles = get_cycles();
+       aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
+       width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
+       x = aligned_x;
+       if ((width <= 0) ||
+           (x + width > dev->info->var.xres) ||
+           (y + height > dev->info->var.yres))
+               return -EINVAL;
+       if (!atomic_read(&dev->usb_active))
+               return 0;
+       urb = dlfb_get_urb(dev);
+       if (!urb)
+               return 0;
+       cmd = urb->transfer_buffer;
+       for (i = y; i < y + height ; i++) {
+               const int line_offset = dev->info->fix.line_length * i;
+               const int byte_offset = line_offset + (x * BPP);
+               if (dlfb_render_hline(dev, &urb,
+                                     (char *) dev->info->fix.smem_start,
+                                     &cmd, byte_offset, width * BPP,
+                                     &bytes_identical, &bytes_sent))
+                       goto error;
+       }
+       if (cmd > (char *) urb->transfer_buffer) {
+               /* Send partial buffer remaining before exiting */
+               int len = cmd - (char *) urb->transfer_buffer;
+               ret = dlfb_submit_urb(dev, urb, len);
+               bytes_sent += len;
+       } else
+               dlfb_urb_completion(urb);
+ error:
+       atomic_add(bytes_sent, &dev->bytes_sent);
+       atomic_add(bytes_identical, &dev->bytes_identical);
+       atomic_add(width*height*2, &dev->bytes_rendered);
+       end_cycles = get_cycles();
+       atomic_add(((unsigned int) ((end_cycles - start_cycles)
+                   >> 10)), /* Kcycles */
+                  &dev->cpu_kcycles_used);
+       return 0;
+ }
+ /*
+  * Path triggered by usermode clients who write to filesystem
+  * e.g. cat filename > /dev/fb1
+  * Not used by X Windows or text-mode console. But useful for testing.
+  * Slow because of extra copy and we must assume all pixels dirty.
+  */
+ static ssize_t dlfb_ops_write(struct fb_info *info, const char __user *buf,
+                         size_t count, loff_t *ppos)
+ {
+       ssize_t result;
+       struct dlfb_data *dev = info->par;
+       u32 offset = (u32) *ppos;
+       result = fb_sys_write(info, buf, count, ppos);
+       if (result > 0) {
+               int start = max((int)(offset / info->fix.line_length) - 1, 0);
+               int lines = min((u32)((result / info->fix.line_length) + 1),
+                               (u32)info->var.yres);
+               dlfb_handle_damage(dev, 0, start, info->var.xres,
+                       lines, info->screen_base);
+       }
+       return result;
+ }
+ /* hardware has native COPY command (see libdlo), but not worth it for fbcon */
+ static void dlfb_ops_copyarea(struct fb_info *info,
+                               const struct fb_copyarea *area)
+ {
+       struct dlfb_data *dev = info->par;
+       sys_copyarea(info, area);
+       dlfb_handle_damage(dev, area->dx, area->dy,
+                       area->width, area->height, info->screen_base);
+ }
+ static void dlfb_ops_imageblit(struct fb_info *info,
+                               const struct fb_image *image)
+ {
+       struct dlfb_data *dev = info->par;
+       sys_imageblit(info, image);
+       dlfb_handle_damage(dev, image->dx, image->dy,
+                       image->width, image->height, info->screen_base);
+ }
+ static void dlfb_ops_fillrect(struct fb_info *info,
+                         const struct fb_fillrect *rect)
+ {
+       struct dlfb_data *dev = info->par;
+       sys_fillrect(info, rect);
+       dlfb_handle_damage(dev, rect->dx, rect->dy, rect->width,
+                             rect->height, info->screen_base);
+ }
+ /*
+  * NOTE: fb_defio.c is holding info->fbdefio.mutex
+  *   Touching ANY framebuffer memory that triggers a page fault
+  *   in fb_defio will cause a deadlock, when it also tries to
+  *   grab the same mutex.
+  */
+ static void dlfb_dpy_deferred_io(struct fb_info *info,
+                               struct list_head *pagelist)
+ {
+       struct page *cur;
+       struct fb_deferred_io *fbdefio = info->fbdefio;
+       struct dlfb_data *dev = info->par;
+       struct urb *urb;
+       char *cmd;
+       cycles_t start_cycles, end_cycles;
+       int bytes_sent = 0;
+       int bytes_identical = 0;
+       int bytes_rendered = 0;
+       if (!fb_defio)
+               return;
+       if (!atomic_read(&dev->usb_active))
+               return;
+       start_cycles = get_cycles();
+       urb = dlfb_get_urb(dev);
+       if (!urb)
+               return;
+       cmd = urb->transfer_buffer;
+       /* walk the written page list and render each to device */
+       list_for_each_entry(cur, &fbdefio->pagelist, lru) {
+               if (dlfb_render_hline(dev, &urb, (char *) info->fix.smem_start,
+                                 &cmd, cur->index << PAGE_SHIFT,
+                                 PAGE_SIZE, &bytes_identical, &bytes_sent))
+                       goto error;
+               bytes_rendered += PAGE_SIZE;
+       }
+       if (cmd > (char *) urb->transfer_buffer) {
+               /* Send partial buffer remaining before exiting */
+               int len = cmd - (char *) urb->transfer_buffer;
+               dlfb_submit_urb(dev, urb, len);
+               bytes_sent += len;
+       } else
+               dlfb_urb_completion(urb);
+ error:
+       atomic_add(bytes_sent, &dev->bytes_sent);
+       atomic_add(bytes_identical, &dev->bytes_identical);
+       atomic_add(bytes_rendered, &dev->bytes_rendered);
+       end_cycles = get_cycles();
+       atomic_add(((unsigned int) ((end_cycles - start_cycles)
+                   >> 10)), /* Kcycles */
+                  &dev->cpu_kcycles_used);
+ }
+ static int dlfb_get_edid(struct dlfb_data *dev, char *edid, int len)
+ {
+       int i;
+       int ret;
+       char *rbuf;
+       rbuf = kmalloc(2, GFP_KERNEL);
+       if (!rbuf)
+               return 0;
+       for (i = 0; i < len; i++) {
+               ret = usb_control_msg(dev->udev,
+                                   usb_rcvctrlpipe(dev->udev, 0), (0x02),
+                                   (0x80 | (0x02 << 5)), i << 8, 0xA1, rbuf, 2,
+                                   HZ);
+               if (ret < 1) {
+                       pr_err("Read EDID byte %d failed err %x\n", i, ret);
+                       i--;
+                       break;
+               }
+               edid[i] = rbuf[1];
+       }
+       kfree(rbuf);
+       return i;
+ }
+ static int dlfb_ops_ioctl(struct fb_info *info, unsigned int cmd,
+                               unsigned long arg)
+ {
+       struct dlfb_data *dev = info->par;
+       struct dloarea *area = NULL;
+       if (!atomic_read(&dev->usb_active))
+               return 0;
+       /* TODO: Update X server to get this from sysfs instead */
+       if (cmd == DLFB_IOCTL_RETURN_EDID) {
+               char *edid = (char *)arg;
+               if (copy_to_user(edid, dev->edid, dev->edid_size))
+                       return -EFAULT;
+               return 0;
+       }
+       /* TODO: Help propose a standard fb.h ioctl to report mmap damage */
+       if (cmd == DLFB_IOCTL_REPORT_DAMAGE) {
+               /*
+                * If we have a damage-aware client, turn fb_defio "off"
+                * To avoid perf imact of unecessary page fault handling.
+                * Done by resetting the delay for this fb_info to a very
+                * long period. Pages will become writable and stay that way.
+                * Reset to normal value when all clients have closed this fb.
+                */
+               if (info->fbdefio)
+                       info->fbdefio->delay = DL_DEFIO_WRITE_DISABLE;
+               area = (struct dloarea *)arg;
+               if (area->x < 0)
+                       area->x = 0;
+               if (area->x > info->var.xres)
+                       area->x = info->var.xres;
+               if (area->y < 0)
+                       area->y = 0;
+               if (area->y > info->var.yres)
+                       area->y = info->var.yres;
+               dlfb_handle_damage(dev, area->x, area->y, area->w, area->h,
+                          info->screen_base);
+       }
+       return 0;
+ }
+ /* taken from vesafb */
+ static int
+ dlfb_ops_setcolreg(unsigned regno, unsigned red, unsigned green,
+              unsigned blue, unsigned transp, struct fb_info *info)
+ {
+       int err = 0;
+       if (regno >= info->cmap.len)
+               return 1;
+       if (regno < 16) {
+               if (info->var.red.offset == 10) {
+                       /* 1:5:5:5 */
+                       ((u32 *) (info->pseudo_palette))[regno] =
+                           ((red & 0xf800) >> 1) |
+                           ((green & 0xf800) >> 6) | ((blue & 0xf800) >> 11);
+               } else {
+                       /* 0:5:6:5 */
+                       ((u32 *) (info->pseudo_palette))[regno] =
+                           ((red & 0xf800)) |
+                           ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
+               }
+       }
+       return err;
+ }
+ /*
+  * It's common for several clients to have framebuffer open simultaneously.
+  * e.g. both fbcon and X. Makes things interesting.
+  * Assumes caller is holding info->lock (for open and release at least)
+  */
+ static int dlfb_ops_open(struct fb_info *info, int user)
+ {
+       struct dlfb_data *dev = info->par;
+       /*
+        * fbcon aggressively connects to first framebuffer it finds,
+        * preventing other clients (X) from working properly. Usually
+        * not what the user wants. Fail by default with option to enable.
+        */
+       if ((user == 0) & (!console))
+               return -EBUSY;
+       /* If the USB device is gone, we don't accept new opens */
+       if (dev->virtualized)
+               return -ENODEV;
+       dev->fb_count++;
+       kref_get(&dev->kref);
+       if (fb_defio && (info->fbdefio == NULL)) {
+               /* enable defio at last moment if not disabled by client */
+               struct fb_deferred_io *fbdefio;
+               fbdefio = kmalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);
+               if (fbdefio) {
+                       fbdefio->delay = DL_DEFIO_WRITE_DELAY;
+                       fbdefio->deferred_io = dlfb_dpy_deferred_io;
+               }
+               info->fbdefio = fbdefio;
+               fb_deferred_io_init(info);
+       }
+       pr_notice("open /dev/fb%d user=%d fb_info=%p count=%d\n",
+           info->node, user, info, dev->fb_count);
+       return 0;
+ }
+ /*
+  * Called when all client interfaces to start transactions have been disabled,
+  * and all references to our device instance (dlfb_data) are released.
+  * Every transaction must have a reference, so we know are fully spun down
+  */
+ static void dlfb_free(struct kref *kref)
+ {
+       struct dlfb_data *dev = container_of(kref, struct dlfb_data, kref);
+       /* this function will wait for all in-flight urbs to complete */
+       if (dev->urbs.count > 0)
+               dlfb_free_urb_list(dev);
+       if (dev->backing_buffer)
+               vfree(dev->backing_buffer);
+       kfree(dev->edid);
+       pr_warn("freeing dlfb_data %p\n", dev);
+       kfree(dev);
+ }
+ static void dlfb_release_urb_work(struct work_struct *work)
+ {
+       struct urb_node *unode = container_of(work, struct urb_node,
+                                             release_urb_work.work);
+       up(&unode->dev->urbs.limit_sem);
+ }
+ static void dlfb_free_framebuffer_work(struct work_struct *work)
+ {
+       struct dlfb_data *dev = container_of(work, struct dlfb_data,
+                                            free_framebuffer_work.work);
+       struct fb_info *info = dev->info;
+       int node = info->node;
+       unregister_framebuffer(info);
+       if (info->cmap.len != 0)
+               fb_dealloc_cmap(&info->cmap);
+       if (info->monspecs.modedb)
+               fb_destroy_modedb(info->monspecs.modedb);
+       if (info->screen_base)
+               vfree(info->screen_base);
+       fb_destroy_modelist(&info->modelist);
+       dev->info = 0;
+       /* Assume info structure is freed after this point */
+       framebuffer_release(info);
+       pr_warn("fb_info for /dev/fb%d has been freed\n", node);
+       /* ref taken in probe() as part of registering framebfufer */
+       kref_put(&dev->kref, dlfb_free);
+ }
+ /*
+  * Assumes caller is holding info->lock mutex (for open and release at least)
+  */
+ static int dlfb_ops_release(struct fb_info *info, int user)
+ {
+       struct dlfb_data *dev = info->par;
+       dev->fb_count--;
+       /* We can't free fb_info here - fbmem will touch it when we return */
+       if (dev->virtualized && (dev->fb_count == 0))
+               schedule_delayed_work(&dev->free_framebuffer_work, HZ);
+       if ((dev->fb_count == 0) && (info->fbdefio)) {
+               fb_deferred_io_cleanup(info);
+               kfree(info->fbdefio);
+               info->fbdefio = NULL;
+               info->fbops->fb_mmap = dlfb_ops_mmap;
+       }
+       pr_warn("released /dev/fb%d user=%d count=%d\n",
+                 info->node, user, dev->fb_count);
+       kref_put(&dev->kref, dlfb_free);
+       return 0;
+ }
+ /*
+  * Check whether a video mode is supported by the DisplayLink chip
+  * We start from monitor's modes, so don't need to filter that here
+  */
+ static int dlfb_is_valid_mode(struct fb_videomode *mode,
+               struct fb_info *info)
+ {
+       struct dlfb_data *dev = info->par;
+       if (mode->xres * mode->yres > dev->sku_pixel_limit) {
+               pr_warn("%dx%d beyond chip capabilities\n",
+                      mode->xres, mode->yres);
+               return 0;
+       }
+       pr_info("%dx%d valid mode\n", mode->xres, mode->yres);
+       return 1;
+ }
+ static void dlfb_var_color_format(struct fb_var_screeninfo *var)
+ {
+       const struct fb_bitfield red = { 11, 5, 0 };
+       const struct fb_bitfield green = { 5, 6, 0 };
+       const struct fb_bitfield blue = { 0, 5, 0 };
+       var->bits_per_pixel = 16;
+       var->red = red;
+       var->green = green;
+       var->blue = blue;
+ }
+ static int dlfb_ops_check_var(struct fb_var_screeninfo *var,
+                               struct fb_info *info)
+ {
+       struct fb_videomode mode;
+       /* TODO: support dynamically changing framebuffer size */
+       if ((var->xres * var->yres * 2) > info->fix.smem_len)
+               return -EINVAL;
+       /* set device-specific elements of var unrelated to mode */
+       dlfb_var_color_format(var);
+       fb_var_to_videomode(&mode, var);
+       if (!dlfb_is_valid_mode(&mode, info))
+               return -EINVAL;
+       return 0;
+ }
+ static int dlfb_ops_set_par(struct fb_info *info)
+ {
+       struct dlfb_data *dev = info->par;
+       int result;
+       u16 *pix_framebuffer;
+       int i;
+       pr_notice("set_par mode %dx%d\n", info->var.xres, info->var.yres);
+       result = dlfb_set_video_mode(dev, &info->var);
+       if ((result == 0) && (dev->fb_count == 0)) {
+               /* paint greenscreen */
+               pix_framebuffer = (u16 *) info->screen_base;
+               for (i = 0; i < info->fix.smem_len / 2; i++)
+                       pix_framebuffer[i] = 0x37e6;
+               dlfb_handle_damage(dev, 0, 0, info->var.xres, info->var.yres,
+                                  info->screen_base);
+       }
+       return result;
+ }
+ /*
+  * In order to come back from full DPMS off, we need to set the mode again
+  */
+ static int dlfb_ops_blank(int blank_mode, struct fb_info *info)
+ {
+       struct dlfb_data *dev = info->par;
+       if (blank_mode != FB_BLANK_UNBLANK) {
+               char *bufptr;
+               struct urb *urb;
+               urb = dlfb_get_urb(dev);
+               if (!urb)
+                       return 0;
+               bufptr = (char *) urb->transfer_buffer;
+               bufptr = dlfb_vidreg_lock(bufptr);
+               bufptr = dlfb_enable_hvsync(bufptr, false);
+               bufptr = dlfb_vidreg_unlock(bufptr);
+               dlfb_submit_urb(dev, urb, bufptr -
+                               (char *) urb->transfer_buffer);
+       } else {
+               dlfb_set_video_mode(dev, &info->var);
+       }
+       return 0;
+ }
+ static struct fb_ops dlfb_ops = {
+       .owner = THIS_MODULE,
+       .fb_read = fb_sys_read,
+       .fb_write = dlfb_ops_write,
+       .fb_setcolreg = dlfb_ops_setcolreg,
+       .fb_fillrect = dlfb_ops_fillrect,
+       .fb_copyarea = dlfb_ops_copyarea,
+       .fb_imageblit = dlfb_ops_imageblit,
+       .fb_mmap = dlfb_ops_mmap,
+       .fb_ioctl = dlfb_ops_ioctl,
+       .fb_open = dlfb_ops_open,
+       .fb_release = dlfb_ops_release,
+       .fb_blank = dlfb_ops_blank,
+       .fb_check_var = dlfb_ops_check_var,
+       .fb_set_par = dlfb_ops_set_par,
+ };
+ /*
+  * Assumes &info->lock held by caller
+  * Assumes no active clients have framebuffer open
+  */
+ static int dlfb_realloc_framebuffer(struct dlfb_data *dev, struct fb_info *info)
+ {
+       int retval = -ENOMEM;
+       int old_len = info->fix.smem_len;
+       int new_len;
+       unsigned char *old_fb = info->screen_base;
+       unsigned char *new_fb;
+       unsigned char *new_back;
+       pr_warn("Reallocating framebuffer. Addresses will change!\n");
+       new_len = info->fix.line_length * info->var.yres;
+       if (PAGE_ALIGN(new_len) > old_len) {
+               /*
+                * Alloc system memory for virtual framebuffer
+                */
+               new_fb = vmalloc(new_len);
+               if (!new_fb) {
+                       pr_err("Virtual framebuffer alloc failed\n");
+                       goto error;
+               }
+               if (info->screen_base) {
+                       memcpy(new_fb, old_fb, old_len);
+                       vfree(info->screen_base);
+               }
+               info->screen_base = new_fb;
+               info->fix.smem_len = PAGE_ALIGN(new_len);
+               info->fix.smem_start = (unsigned long) new_fb;
+               info->flags = udlfb_info_flags;
+               /*
+                * Second framebuffer copy to mirror the framebuffer state
+                * on the physical USB device. We can function without this.
+                * But with imperfect damage info we may send pixels over USB
+                * that were, in fact, unchanged - wasting limited USB bandwidth
+                */
+               new_back = vmalloc(new_len);
+               if (!new_back)
+                       pr_info("No shadow/backing buffer allcoated\n");
+               else {
+                       if (dev->backing_buffer)
+                               vfree(dev->backing_buffer);
+                       dev->backing_buffer = new_back;
+                       memset(dev->backing_buffer, 0, new_len);
+               }
+       }
+       retval = 0;
+ error:
+       return retval;
+ }
+ /*
+  * 1) Get EDID from hw, or use sw default
+  * 2) Parse into various fb_info structs
+  * 3) Allocate virtual framebuffer memory to back highest res mode
+  *
+  * Parses EDID into three places used by various parts of fbdev:
+  * fb_var_screeninfo contains the timing of the monitor's preferred mode
+  * fb_info.monspecs is full parsed EDID info, including monspecs.modedb
+  * fb_info.modelist is a linked list of all monitor & VESA modes which work
+  *
+  * If EDID is not readable/valid, then modelist is all VESA modes,
+  * monspecs is NULL, and fb_var_screeninfo is set to safe VESA mode
+  * Returns 0 if successful
+  */
+ static int dlfb_setup_modes(struct dlfb_data *dev,
+                          struct fb_info *info,
+                          char *default_edid, size_t default_edid_size)
+ {
+       int i;
+       const struct fb_videomode *default_vmode = NULL;
+       int result = 0;
+       char *edid;
+       int tries = 3;
+       if (info->dev) /* only use mutex if info has been registered */
+               mutex_lock(&info->lock);
+       edid = kmalloc(EDID_LENGTH, GFP_KERNEL);
+       if (!edid) {
+               result = -ENOMEM;
+               goto error;
+       }
+       fb_destroy_modelist(&info->modelist);
+       memset(&info->monspecs, 0, sizeof(info->monspecs));
+       /*
+        * Try to (re)read EDID from hardware first
+        * EDID data may return, but not parse as valid
+        * Try again a few times, in case of e.g. analog cable noise
+        */
+       while (tries--) {
+               i = dlfb_get_edid(dev, edid, EDID_LENGTH);
+               if (i >= EDID_LENGTH)
+                       fb_edid_to_monspecs(edid, &info->monspecs);
+               if (info->monspecs.modedb_len > 0) {
+                       dev->edid = edid;
+                       dev->edid_size = i;
+                       break;
+               }
+       }
+       /* If that fails, use a previously returned EDID if available */
+       if (info->monspecs.modedb_len == 0) {
+               pr_err("Unable to get valid EDID from device/display\n");
+               if (dev->edid) {
+                       fb_edid_to_monspecs(dev->edid, &info->monspecs);
+                       if (info->monspecs.modedb_len > 0)
+                               pr_err("Using previously queried EDID\n");
+               }
+       }
+       /* If that fails, use the default EDID we were handed */
+       if (info->monspecs.modedb_len == 0) {
+               if (default_edid_size >= EDID_LENGTH) {
+                       fb_edid_to_monspecs(default_edid, &info->monspecs);
+                       if (info->monspecs.modedb_len > 0) {
+                               memcpy(edid, default_edid, default_edid_size);
+                               dev->edid = edid;
+                               dev->edid_size = default_edid_size;
+                               pr_err("Using default/backup EDID\n");
+                       }
+               }
+       }
+       /* If we've got modes, let's pick a best default mode */
+       if (info->monspecs.modedb_len > 0) {
+               for (i = 0; i < info->monspecs.modedb_len; i++) {
+                       if (dlfb_is_valid_mode(&info->monspecs.modedb[i], info))
+                               fb_add_videomode(&info->monspecs.modedb[i],
+                                       &info->modelist);
+                       else /* if we've removed top/best mode */
+                               info->monspecs.misc &= ~FB_MISC_1ST_DETAIL;
+               }
+               default_vmode = fb_find_best_display(&info->monspecs,
+                                                    &info->modelist);
+       }
+       /* If everything else has failed, fall back to safe default mode */
+       if (default_vmode == NULL) {
+               struct fb_videomode fb_vmode = {0};
+               /*
+                * Add the standard VESA modes to our modelist
+                * Since we don't have EDID, there may be modes that
+                * overspec monitor and/or are incorrect aspect ratio, etc.
+                * But at least the user has a chance to choose
+                */
+               for (i = 0; i < VESA_MODEDB_SIZE; i++) {
+                       if (dlfb_is_valid_mode((struct fb_videomode *)
+                                               &vesa_modes[i], info))
+                               fb_add_videomode(&vesa_modes[i],
+                                                &info->modelist);
+               }
+               /*
+                * default to resolution safe for projectors
+                * (since they are most common case without EDID)
+                */
+               fb_vmode.xres = 800;
+               fb_vmode.yres = 600;
+               fb_vmode.refresh = 60;
+               default_vmode = fb_find_nearest_mode(&fb_vmode,
+                                                    &info->modelist);
+       }
+       /* If we have good mode and no active clients*/
+       if ((default_vmode != NULL) && (dev->fb_count == 0)) {
+               fb_videomode_to_var(&info->var, default_vmode);
+               dlfb_var_color_format(&info->var);
+               /*
+                * with mode size info, we can now alloc our framebuffer.
+                */
+               memcpy(&info->fix, &dlfb_fix, sizeof(dlfb_fix));
+               info->fix.line_length = info->var.xres *
+                       (info->var.bits_per_pixel / 8);
+               result = dlfb_realloc_framebuffer(dev, info);
+       } else
+               result = -EINVAL;
+ error:
+       if (edid && (dev->edid != edid))
+               kfree(edid);
+       if (info->dev)
+               mutex_unlock(&info->lock);
+       return result;
+ }
+ static ssize_t metrics_bytes_rendered_show(struct device *fbdev,
+                                  struct device_attribute *a, char *buf) {
+       struct fb_info *fb_info = dev_get_drvdata(fbdev);
+       struct dlfb_data *dev = fb_info->par;
+       return snprintf(buf, PAGE_SIZE, "%u\n",
+                       atomic_read(&dev->bytes_rendered));
+ }
+ static ssize_t metrics_bytes_identical_show(struct device *fbdev,
+                                  struct device_attribute *a, char *buf) {
+       struct fb_info *fb_info = dev_get_drvdata(fbdev);
+       struct dlfb_data *dev = fb_info->par;
+       return snprintf(buf, PAGE_SIZE, "%u\n",
+                       atomic_read(&dev->bytes_identical));
+ }
+ static ssize_t metrics_bytes_sent_show(struct device *fbdev,
+                                  struct device_attribute *a, char *buf) {
+       struct fb_info *fb_info = dev_get_drvdata(fbdev);
+       struct dlfb_data *dev = fb_info->par;
+       return snprintf(buf, PAGE_SIZE, "%u\n",
+                       atomic_read(&dev->bytes_sent));
+ }
+ static ssize_t metrics_cpu_kcycles_used_show(struct device *fbdev,
+                                  struct device_attribute *a, char *buf) {
+       struct fb_info *fb_info = dev_get_drvdata(fbdev);
+       struct dlfb_data *dev = fb_info->par;
+       return snprintf(buf, PAGE_SIZE, "%u\n",
+                       atomic_read(&dev->cpu_kcycles_used));
+ }
+ static ssize_t edid_show(
+                       struct file *filp,
+                       struct kobject *kobj, struct bin_attribute *a,
+                        char *buf, loff_t off, size_t count) {
+       struct device *fbdev = container_of(kobj, struct device, kobj);
+       struct fb_info *fb_info = dev_get_drvdata(fbdev);
+       struct dlfb_data *dev = fb_info->par;
+       if (dev->edid == NULL)
+               return 0;
+       if ((off >= dev->edid_size) || (count > dev->edid_size))
+               return 0;
+       if (off + count > dev->edid_size)
+               count = dev->edid_size - off;
+       pr_info("sysfs edid copy %p to %p, %d bytes\n",
+               dev->edid, buf, (int) count);
+       memcpy(buf, dev->edid, count);
+       return count;
+ }
+ static ssize_t edid_store(
+                       struct file *filp,
+                       struct kobject *kobj, struct bin_attribute *a,
+                       char *src, loff_t src_off, size_t src_size) {
+       struct device *fbdev = container_of(kobj, struct device, kobj);
+       struct fb_info *fb_info = dev_get_drvdata(fbdev);
+       struct dlfb_data *dev = fb_info->par;
+       /* We only support write of entire EDID at once, no offset*/
+       if ((src_size != EDID_LENGTH) || (src_off != 0))
+               return 0;
+       dlfb_setup_modes(dev, fb_info, src, src_size);
+       if (dev->edid && (memcmp(src, dev->edid, src_size) == 0)) {
+               pr_info("sysfs written EDID is new default\n");
+               dlfb_ops_set_par(fb_info);
+               return src_size;
+       } else
+               return 0;
+ }
+ static ssize_t metrics_reset_store(struct device *fbdev,
+                          struct device_attribute *attr,
+                          const char *buf, size_t count)
+ {
+       struct fb_info *fb_info = dev_get_drvdata(fbdev);
+       struct dlfb_data *dev = fb_info->par;
+       atomic_set(&dev->bytes_rendered, 0);
+       atomic_set(&dev->bytes_identical, 0);
+       atomic_set(&dev->bytes_sent, 0);
+       atomic_set(&dev->cpu_kcycles_used, 0);
+       return count;
+ }
+ static struct bin_attribute edid_attr = {
+       .attr.name = "edid",
+       .attr.mode = 0666,
+       .size = EDID_LENGTH,
+       .read = edid_show,
+       .write = edid_store
+ };
+ static struct device_attribute fb_device_attrs[] = {
+       __ATTR_RO(metrics_bytes_rendered),
+       __ATTR_RO(metrics_bytes_identical),
+       __ATTR_RO(metrics_bytes_sent),
+       __ATTR_RO(metrics_cpu_kcycles_used),
++      __ATTR(metrics_reset, S_IWUSR, NULL, metrics_reset_store),
+ };
+ /*
+  * This is necessary before we can communicate with the display controller.
+  */
+ static int dlfb_select_std_channel(struct dlfb_data *dev)
+ {
+       int ret;
+       u8 set_def_chn[] = {       0x57, 0xCD, 0xDC, 0xA7,
+                               0x1C, 0x88, 0x5E, 0x15,
+                               0x60, 0xFE, 0xC6, 0x97,
+                               0x16, 0x3D, 0x47, 0xF2  };
+       ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
+                       NR_USB_REQUEST_CHANNEL,
+                       (USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
+                       set_def_chn, sizeof(set_def_chn), USB_CTRL_SET_TIMEOUT);
+       return ret;
+ }
+ static int dlfb_parse_vendor_descriptor(struct dlfb_data *dev,
+                                       struct usb_device *usbdev)
+ {
+       char *desc;
+       char *buf;
+       char *desc_end;
+       u8 total_len = 0;
+       buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
+       if (!buf)
+               return false;
+       desc = buf;
+       total_len = usb_get_descriptor(usbdev, 0x5f, /* vendor specific */
+                                   0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
+       if (total_len > 5) {
+               pr_info("vendor descriptor length:%x data:%02x %02x %02x %02x" \
+                       "%02x %02x %02x %02x %02x %02x %02x\n",
+                       total_len, desc[0],
+                       desc[1], desc[2], desc[3], desc[4], desc[5], desc[6],
+                       desc[7], desc[8], desc[9], desc[10]);
+               if ((desc[0] != total_len) || /* descriptor length */
+                   (desc[1] != 0x5f) ||   /* vendor descriptor type */
+                   (desc[2] != 0x01) ||   /* version (2 bytes) */
+                   (desc[3] != 0x00) ||
+                   (desc[4] != total_len - 2)) /* length after type */
+                       goto unrecognized;
+               desc_end = desc + total_len;
+               desc += 5; /* the fixed header we've already parsed */
+               while (desc < desc_end) {
+                       u8 length;
+                       u16 key;
+                       key = *((u16 *) desc);
+                       desc += sizeof(u16);
+                       length = *desc;
+                       desc++;
+                       switch (key) {
+                       case 0x0200: { /* max_area */
+                               u32 max_area;
+                               max_area = le32_to_cpu(*((u32 *)desc));
+                               pr_warn("DL chip limited to %d pixel modes\n",
+                                       max_area);
+                               dev->sku_pixel_limit = max_area;
+                               break;
+                       }
+                       default:
+                               break;
+                       }
+                       desc += length;
+               }
+       }
+       goto success;
+ unrecognized:
+       /* allow udlfb to load for now even if firmware unrecognized */
+       pr_err("Unrecognized vendor firmware descriptor\n");
+ success:
+       kfree(buf);
+       return true;
+ }
+ static int dlfb_usb_probe(struct usb_interface *interface,
+                       const struct usb_device_id *id)
+ {
+       struct usb_device *usbdev;
+       struct dlfb_data *dev = 0;
+       struct fb_info *info = 0;
+       int retval = -ENOMEM;
+       int i;
+       /* usb initialization */
+       usbdev = interface_to_usbdev(interface);
+       dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+       if (dev == NULL) {
+               err("dlfb_usb_probe: failed alloc of dev struct\n");
+               goto error;
+       }
+       /* we need to wait for both usb and fbdev to spin down on disconnect */
+       kref_init(&dev->kref); /* matching kref_put in usb .disconnect fn */
+       kref_get(&dev->kref); /* matching kref_put in free_framebuffer_work */
+       dev->udev = usbdev;
+       dev->gdev = &usbdev->dev; /* our generic struct device * */
+       usb_set_intfdata(interface, dev);
+       pr_info("%s %s - serial #%s\n",
+               usbdev->manufacturer, usbdev->product, usbdev->serial);
+       pr_info("vid_%04x&pid_%04x&rev_%04x driver's dlfb_data struct at %p\n",
+               usbdev->descriptor.idVendor, usbdev->descriptor.idProduct,
+               usbdev->descriptor.bcdDevice, dev);
+       pr_info("console enable=%d\n", console);
+       pr_info("fb_defio enable=%d\n", fb_defio);
+       dev->sku_pixel_limit = 2048 * 1152; /* default to maximum */
+       if (!dlfb_parse_vendor_descriptor(dev, usbdev)) {
+               pr_err("firmware not recognized. Assume incompatible device\n");
+               goto error;
+       }
+       if (!dlfb_alloc_urb_list(dev, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
+               retval = -ENOMEM;
+               pr_err("dlfb_alloc_urb_list failed\n");
+               goto error;
+       }
+       /* We don't register a new USB class. Our client interface is fbdev */
+       /* allocates framebuffer driver structure, not framebuffer memory */
+       info = framebuffer_alloc(0, &usbdev->dev);
+       if (!info) {
+               retval = -ENOMEM;
+               pr_err("framebuffer_alloc failed\n");
+               goto error;
+       }
+       dev->info = info;
+       info->par = dev;
+       info->pseudo_palette = dev->pseudo_palette;
+       info->fbops = &dlfb_ops;
+       retval = fb_alloc_cmap(&info->cmap, 256, 0);
+       if (retval < 0) {
+               pr_err("fb_alloc_cmap failed %x\n", retval);
+               goto error;
+       }
+       INIT_DELAYED_WORK(&dev->free_framebuffer_work,
+                         dlfb_free_framebuffer_work);
+       INIT_LIST_HEAD(&info->modelist);
+       retval = dlfb_setup_modes(dev, info, NULL, 0);
+       if (retval != 0) {
+               pr_err("unable to find common mode for display and adapter\n");
+               goto error;
+       }
+       /* ready to begin using device */
+       atomic_set(&dev->usb_active, 1);
+       dlfb_select_std_channel(dev);
+       dlfb_ops_check_var(&info->var, info);
+       dlfb_ops_set_par(info);
+       retval = register_framebuffer(info);
+       if (retval < 0) {
+               pr_err("register_framebuffer failed %d\n", retval);
+               goto error;
+       }
+       for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
+               device_create_file(info->dev, &fb_device_attrs[i]);
+       device_create_bin_file(info->dev, &edid_attr);
+       pr_info("DisplayLink USB device /dev/fb%d attached. %dx%d resolution."
+                       " Using %dK framebuffer memory\n", info->node,
+                       info->var.xres, info->var.yres,
+                       ((dev->backing_buffer) ?
+                       info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
+       return 0;
+ error:
+       if (dev) {
+               if (info) {
+                       if (info->cmap.len != 0)
+                               fb_dealloc_cmap(&info->cmap);
+                       if (info->monspecs.modedb)
+                               fb_destroy_modedb(info->monspecs.modedb);
+                       if (info->screen_base)
+                               vfree(info->screen_base);
+                       fb_destroy_modelist(&info->modelist);
+                       framebuffer_release(info);
+               }
+               if (dev->backing_buffer)
+                       vfree(dev->backing_buffer);
+               kref_put(&dev->kref, dlfb_free); /* ref for framebuffer */
+               kref_put(&dev->kref, dlfb_free); /* last ref from kref_init */
+               /* dev has been deallocated. Do not dereference */
+       }
+       return retval;
+ }
+ static void dlfb_usb_disconnect(struct usb_interface *interface)
+ {
+       struct dlfb_data *dev;
+       struct fb_info *info;
+       int i;
+       dev = usb_get_intfdata(interface);
+       info = dev->info;
+       pr_info("USB disconnect starting\n");
+       /* we virtualize until all fb clients release. Then we free */
+       dev->virtualized = true;
+       /* When non-active we'll update virtual framebuffer, but no new urbs */
+       atomic_set(&dev->usb_active, 0);
+       /* remove udlfb's sysfs interfaces */
+       for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
+               device_remove_file(info->dev, &fb_device_attrs[i]);
+       device_remove_bin_file(info->dev, &edid_attr);
+       usb_set_intfdata(interface, NULL);
+       /* if clients still have us open, will be freed on last close */
+       if (dev->fb_count == 0)
+               schedule_delayed_work(&dev->free_framebuffer_work, 0);
+       /* release reference taken by kref_init in probe() */
+       kref_put(&dev->kref, dlfb_free);
+       /* consider dlfb_data freed */
+       return;
+ }
+ static struct usb_driver dlfb_driver = {
+       .name = "udlfb",
+       .probe = dlfb_usb_probe,
+       .disconnect = dlfb_usb_disconnect,
+       .id_table = id_table,
+ };
+ static int __init dlfb_module_init(void)
+ {
+       int res;
+       res = usb_register(&dlfb_driver);
+       if (res)
+               err("usb_register failed. Error number %d", res);
+       return res;
+ }
+ static void __exit dlfb_module_exit(void)
+ {
+       usb_deregister(&dlfb_driver);
+ }
+ module_init(dlfb_module_init);
+ module_exit(dlfb_module_exit);
+ static void dlfb_urb_completion(struct urb *urb)
+ {
+       struct urb_node *unode = urb->context;
+       struct dlfb_data *dev = unode->dev;
+       unsigned long flags;
+       /* sync/async unlink faults aren't errors */
+       if (urb->status) {
+               if (!(urb->status == -ENOENT ||
+                   urb->status == -ECONNRESET ||
+                   urb->status == -ESHUTDOWN)) {
+                       pr_err("%s - nonzero write bulk status received: %d\n",
+                               __func__, urb->status);
+                       atomic_set(&dev->lost_pixels, 1);
+               }
+       }
+       urb->transfer_buffer_length = dev->urbs.size; /* reset to actual */
+       spin_lock_irqsave(&dev->urbs.lock, flags);
+       list_add_tail(&unode->entry, &dev->urbs.list);
+       dev->urbs.available++;
+       spin_unlock_irqrestore(&dev->urbs.lock, flags);
+       /*
+        * When using fb_defio, we deadlock if up() is called
+        * while another is waiting. So queue to another process.
+        */
+       if (fb_defio)
+               schedule_delayed_work(&unode->release_urb_work, 0);
+       else
+               up(&dev->urbs.limit_sem);
+ }
+ static void dlfb_free_urb_list(struct dlfb_data *dev)
+ {
+       int count = dev->urbs.count;
+       struct list_head *node;
+       struct urb_node *unode;
+       struct urb *urb;
+       int ret;
+       unsigned long flags;
+       pr_notice("Waiting for completes and freeing all render urbs\n");
+       /* keep waiting and freeing, until we've got 'em all */
+       while (count--) {
+               /* Getting interrupted means a leak, but ok at shutdown*/
+               ret = down_interruptible(&dev->urbs.limit_sem);
+               if (ret)
+                       break;
+               spin_lock_irqsave(&dev->urbs.lock, flags);
+               node = dev->urbs.list.next; /* have reserved one with sem */
+               list_del_init(node);
+               spin_unlock_irqrestore(&dev->urbs.lock, flags);
+               unode = list_entry(node, struct urb_node, entry);
+               urb = unode->urb;
+               /* Free each separately allocated piece */
+               usb_free_coherent(urb->dev, dev->urbs.size,
+                                 urb->transfer_buffer, urb->transfer_dma);
+               usb_free_urb(urb);
+               kfree(node);
+       }
+ }
+ static int dlfb_alloc_urb_list(struct dlfb_data *dev, int count, size_t size)
+ {
+       int i = 0;
+       struct urb *urb;
+       struct urb_node *unode;
+       char *buf;
+       spin_lock_init(&dev->urbs.lock);
+       dev->urbs.size = size;
+       INIT_LIST_HEAD(&dev->urbs.list);
+       while (i < count) {
+               unode = kzalloc(sizeof(struct urb_node), GFP_KERNEL);
+               if (!unode)
+                       break;
+               unode->dev = dev;
+               INIT_DELAYED_WORK(&unode->release_urb_work,
+                         dlfb_release_urb_work);
+               urb = usb_alloc_urb(0, GFP_KERNEL);
+               if (!urb) {
+                       kfree(unode);
+                       break;
+               }
+               unode->urb = urb;
+               buf = usb_alloc_coherent(dev->udev, MAX_TRANSFER, GFP_KERNEL,
+                                        &urb->transfer_dma);
+               if (!buf) {
+                       kfree(unode);
+                       usb_free_urb(urb);
+                       break;
+               }
+               /* urb->transfer_buffer_length set to actual before submit */
+               usb_fill_bulk_urb(urb, dev->udev, usb_sndbulkpipe(dev->udev, 1),
+                       buf, size, dlfb_urb_completion, unode);
+               urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+               list_add_tail(&unode->entry, &dev->urbs.list);
+               i++;
+       }
+       sema_init(&dev->urbs.limit_sem, i);
+       dev->urbs.count = i;
+       dev->urbs.available = i;
+       pr_notice("allocated %d %d byte urbs\n", i, (int) size);
+       return i;
+ }
+ static struct urb *dlfb_get_urb(struct dlfb_data *dev)
+ {
+       int ret = 0;
+       struct list_head *entry;
+       struct urb_node *unode;
+       struct urb *urb = NULL;
+       unsigned long flags;
+       /* Wait for an in-flight buffer to complete and get re-queued */
+       ret = down_timeout(&dev->urbs.limit_sem, GET_URB_TIMEOUT);
+       if (ret) {
+               atomic_set(&dev->lost_pixels, 1);
+               pr_warn("wait for urb interrupted: %x available: %d\n",
+                      ret, dev->urbs.available);
+               goto error;
+       }
+       spin_lock_irqsave(&dev->urbs.lock, flags);
+       BUG_ON(list_empty(&dev->urbs.list)); /* reserved one with limit_sem */
+       entry = dev->urbs.list.next;
+       list_del_init(entry);
+       dev->urbs.available--;
+       spin_unlock_irqrestore(&dev->urbs.lock, flags);
+       unode = list_entry(entry, struct urb_node, entry);
+       urb = unode->urb;
+ error:
+       return urb;
+ }
+ static int dlfb_submit_urb(struct dlfb_data *dev, struct urb *urb, size_t len)
+ {
+       int ret;
+       BUG_ON(len > dev->urbs.size);
+       urb->transfer_buffer_length = len; /* set to actual payload len */
+       ret = usb_submit_urb(urb, GFP_KERNEL);
+       if (ret) {
+               dlfb_urb_completion(urb); /* because no one else will */
+               atomic_set(&dev->lost_pixels, 1);
+               pr_err("usb_submit_urb error %x\n", ret);
+       }
+       return ret;
+ }
+ module_param(console, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
+ MODULE_PARM_DESC(console, "Allow fbcon to consume first framebuffer found");
+ module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
+ MODULE_PARM_DESC(fb_defio, "Enable fb_defio mmap support. *Experimental*");
+ MODULE_AUTHOR("Roberto De Ioris <roberto@unbit.it>, "
+             "Jaya Kumar <jayakumar.lkml@gmail.com>, "
+             "Bernie Thompson <bernie@plugable.com>");
+ MODULE_DESCRIPTION("DisplayLink kernel framebuffer driver");
+ MODULE_LICENSE("GPL");