linux-kernel - Re: [PATCH v2] i2c: cadence: fixup of wait_for_completion

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Date:	Tue, 10 Feb 2015 17:17:24 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Nicholas Mc Guire <hofrat@...dl.org>,
	Michal Simek <michal.simek@...inx.com>
CC:	Soren Brinkmann <soren.brinkmann@...inx.com>,
	Wolfram Sang <wsa@...-dreams.de>, linux-kernel@...r.kernel.org,
	linux-i2c@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] i2c: cadence: fixup of wait_for_completion_timeout
 return handling

Hello.

On 2/9/2015 6:03 PM, Nicholas Mc Guire wrote:

> return type of wait_for_completion_timeout is unsigned long not int. The
> return variable is renamed to reflect its use and the type adjusted to
> unsigned long.

> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> ---

> v2: int ret is an idiom not only a declaration - thus rather than just
>      changing the type, rename the variable, as suggested by Wolfram Sang
>      <wsa@...-dreams.de>.

> Patch was only compile tested with multi_v7_defconfig
> (implies CONFIG_I2C_CADENCE=y)

> Patch is against 3.19.0-rc7 (localversion-next is -next-20150209)

>   drivers/i2c/busses/i2c-cadence.c |    6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)

> diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
> index 7d7a14c..8f92732f 100644
> --- a/drivers/i2c/busses/i2c-cadence.c
> +++ b/drivers/i2c/busses/i2c-cadence.c
> @@ -475,7 +475,7 @@ static void cdns_i2c_master_reset(struct i2c_adapter *adap)
>   static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
>   		struct i2c_adapter *adap)
>   {
> -	int ret;
> +	unsigned long timeout;
>   	u32 reg;
>
>   	id->p_msg = msg;
> @@ -501,8 +501,8 @@ static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
>   		cdns_i2c_msend(id);
>
>   	/* Wait for the signal of completion */
> -	ret = wait_for_completion_timeout(&id->xfer_done, adap->timeout);
> -	if (!ret) {
> +	timeout = wait_for_completion_timeout(&id->xfer_done, adap->timeout);
> +	if (!timeout) {

    Which means that timeout *did* expire, contrary to what one may think. I 
don't think this is a good name for the variable, I'd suggest something like 
'time_left' instead...

>   		cdns_i2c_master_reset(adap);
>   		dev_err(id->adap.dev.parent,
>   				"timeout waiting on completion\n");

WBR, Sergei

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