Merge branch 'i2c-embedded/for-3.3' of git://git.pengutronix.de/git/wsa/linux-2.6
authorLinus Torvalds <torvalds@linux-foundation.org>
Fri, 2 Mar 2012 02:24:52 +0000 (18:24 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 2 Mar 2012 02:24:52 +0000 (18:24 -0800)
i2c bugfix from Wolfram Sang:
  "This patch fixes a wrong assumption in the mxs-i2c-driver about a
   command queue being done.  Without it, we have seen races when the
   bus was under load."

* 'i2c-embedded/for-3.3' of git://git.pengutronix.de/git/wsa/linux-2.6:
  i2c: mxs: only flag completion when queue is completely done

drivers/i2c/busses/i2c-mxs.c

index 7e78f7c87857c7f0d7af5417064f19e822b4a5f4..3d471d56bf15d1faf295f606c31f19d90f384e79 100644 (file)
@@ -72,6 +72,7 @@
 
 #define MXS_I2C_QUEUESTAT      (0x70)
 #define MXS_I2C_QUEUESTAT_RD_QUEUE_EMPTY        0x00002000
+#define MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK 0x0000001F
 
 #define MXS_I2C_QUEUECMD       (0x80)
 
@@ -219,14 +220,14 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
        int ret;
        int flags;
 
-       init_completion(&i2c->cmd_complete);
-
        dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
                msg->addr, msg->len, msg->flags, stop);
 
        if (msg->len == 0)
                return -EINVAL;
 
+       init_completion(&i2c->cmd_complete);
+
        flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
 
        if (msg->flags & I2C_M_RD)
@@ -286,6 +287,7 @@ static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
 {
        struct mxs_i2c_dev *i2c = dev_id;
        u32 stat = readl(i2c->regs + MXS_I2C_CTRL1) & MXS_I2C_IRQ_MASK;
+       bool is_last_cmd;
 
        if (!stat)
                return IRQ_NONE;
@@ -300,9 +302,14 @@ static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
        else
                i2c->cmd_err = 0;
 
-       complete(&i2c->cmd_complete);
+       is_last_cmd = (readl(i2c->regs + MXS_I2C_QUEUESTAT) &
+               MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK) == 0;
+
+       if (is_last_cmd || i2c->cmd_err)
+               complete(&i2c->cmd_complete);
 
        writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
+
        return IRQ_HANDLED;
 }