linux-kernel - Re: [PATCH] i2c-imx: do not allow interruptions when waiting for I2C to complete

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Date:	Thu, 27 May 2010 13:49:48 +0200
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	Marc Kleine-Budde <mkl@...gutronix.de>
Cc:	sha@...gutronix.de,
	"Jean Delvare (PC drivers, core)" <khali@...ux-fr.org>,
	"Ben Dooks (embedded platforms)" <ben-linux@...ff.org>,
	Richard Zhao <linuxzsc@...il.com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Arnaud Patard <apatard@...driva.com>,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c-imx: do not allow interruptions when waiting for
	I2C to complete

On Thu, May 27, 2010 at 01:36:27PM +0200, Marc Kleine-Budde wrote:
> The i2c_imx_trx_complete() function is using
> wait_event_interruptible_timeout() to wait for the I2C controller to
> signal that it has completed an I2C bus operation. If the process that
> causes the I2C operation receives a signal, the wait will be
> interrupted, returning an error. It is better to let the I2C operation
> finished before handling the signal (i.e. returning into userspace).
> 
> It is safe to use wait_event_timeout() instead, because the timeout
> will allow the process to exit if the I2C bus hangs. It's also better
> to allow the I2C operation to finish, because unacknowledged I2C
> operations can cause the I2C bus to hang.
> 
> Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
> ---
>  drivers/i2c/busses/i2c-imx.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index d1ff940..d7051fe 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -161,7 +161,7 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx)
>  {
>  	int result;
>  
> -	result = wait_event_interruptible_timeout(i2c_imx->queue,
> +	result = wait_event_timeout(i2c_imx->queue,
>  		i2c_imx->i2csr & I2SR_IIF, HZ / 10);
>  
>  	if (unlikely(result < 0)) {

That 'if' can go, too. wait_event_timeout does not return neg values.

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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