[PATCH] ARM: OMAP: Fix occasional i2c driver hang

[PATCH] ARM: OMAP: Fix occasional i2c driver hang

[Jason Marini]

The i2c driver contains a while loop that has no timeout.  If i2c is in a
funky state and OMAP_I2C_CON_STT remains asserted, the kernel hangs.  Insert
the standard i2c timeout into the loop.

Signed-off-by: Jason P Marini <jason.marini@gmail.com>
---
 drivers/i2c/busses/i2c-omap.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 3c4e581..3a7b6ef 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -440,9 +440,16 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
 	omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);

 	if (dev->b_hw && stop) {
+		unsigned long delay = jiffies + OMAP_I2C_TIMEOUT;
+
 		/* H/w behavior: dont write stt and stp together.. */
 		while (omap_i2c_read_reg(dev, OMAP_I2C_CON_REG) & OMAP_I2C_CON_STT) {
-			/* Dont do anything - this will come in a couple of loops at max*/
+			/* Let the user know if i2c is in a bad state */
+			if (time_after (jiffies, delay)) {
+				dev_err(dev->dev, "controller timed out "
+				"waiting for start condition to finish\n");
+				return -ETIMEDOUT;
+			}
 		}
 		w |= OMAP_I2C_CON_STP;
 		w &= ~OMAP_I2C_CON_STT;
-- 
1.5.5.1

Re: [PATCH] ARM: OMAP: Fix occasional i2c driver hang

[Tony Lindgren]

* Jason Marini <jason.marini@gmail.com> [080828 12:31]:
> The i2c driver contains a while loop that has no timeout.  If i2c is in a
> funky state and OMAP_I2C_CON_STT remains asserted, the kernel hangs.  Insert
> the standard i2c timeout into the loop.

Pushing today.

Tony


> Signed-off-by: Jason P Marini <jason.marini@gmail.com>
> ---
>  drivers/i2c/busses/i2c-omap.c |    9 ++++++++-
>  1 files changed, 8 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 3c4e581..3a7b6ef 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -440,9 +440,16 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
>  	omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
> 
>  	if (dev->b_hw && stop) {
> +		unsigned long delay = jiffies + OMAP_I2C_TIMEOUT;
> +
>  		/* H/w behavior: dont write stt and stp together.. */
>  		while (omap_i2c_read_reg(dev, OMAP_I2C_CON_REG) & OMAP_I2C_CON_STT) {
> -			/* Dont do anything - this will come in a couple of loops at max*/
> +			/* Let the user know if i2c is in a bad state */
> +			if (time_after (jiffies, delay)) {
> +				dev_err(dev->dev, "controller timed out "
> +				"waiting for start condition to finish\n");
> +				return -ETIMEDOUT;
> +			}
>  		}
>  		w |= OMAP_I2C_CON_STP;
>  		w &= ~OMAP_I2C_CON_STT;
> -- 
> 1.5.5.1
> --
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