linux-kernel - Re: i2c: designware: prevent signals from aborting I2C transfers

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Date:	Fri, 7 Jun 2013 10:53:39 +0200
From:	Christian Ruppert <christian.ruppert@...lis.com>
To:	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org, Wolfram Sang <wsa@...-dreams.de>,
	Jean Delvare <khali@...ux-fr.org>, linux-i2c@...r.kernel.org
Subject: Re: i2c: designware: prevent signals from aborting I2C transfers

On Wed, May 22, 2013 at 10:03:11AM -0000, Mika Westerberg wrote:
> If a process receives signal while it is waiting for I2C transfer to
> complete, an error is returned to the caller and the transfer is aborted.
> This can cause the driver to fail subsequent transfers. Also according to
> commit d295a86eab2 (i2c: mv64xxx: work around signals causing I2C
> transactions to be aborted) I2C drivers aren't supposed to abort
> transactions on signals.
> 
> To prevent this switch to use wait_for_completion_timeout() instead of
> wait_for_completion_interruptible_timeout() in the designware I2C driver.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
Reviewed-by: Christian Ruppert <christian.ruppert@...lis.com>
> 
> ---
> drivers/i2c/busses/i2c-designware-core.c |    5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> index c41ca63..db20a28 100644
> --- a/drivers/i2c/busses/i2c-designware-core.c
> +++ b/drivers/i2c/busses/i2c-designware-core.c
> @@ -580,14 +580,13 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>  	i2c_dw_xfer_init(dev);
>  
>  	/* wait for tx to complete */
> -	ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete, HZ);
> +	ret = wait_for_completion_timeout(&dev->cmd_complete, HZ);
>  	if (ret == 0) {
>  		dev_err(dev->dev, "controller timed out\n");
>  		i2c_dw_init(dev);
>  		ret = -ETIMEDOUT;
>  		goto done;
> -	} else if (ret < 0)
> -		goto done;
> +	}
>  
>  	if (dev->msg_err) {
>  		ret = dev->msg_err;

-- 
  Christian Ruppert              ,          <christian.ruppert@...lis.com>
                                /|
  Tel: +41/(0)22 816 19-42     //|                 3, Chemin du Pré-Fleuri
                             _// | bilis Systems   CH-1228 Plan-les-Ouates
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