linux-kernel - Re: [PATCH] i2c: mv64xxx: remove unreachable signal case handling

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Message-ID: <20150617130030.GG13393@katana>
Date:	Wed, 17 Jun 2015 15:00:30 +0200
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Nicholas Mc Guire <hofrat@...dl.org>
Cc:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Andrew Lunn <andrew@...n.ch>, Chen-Yu Tsai <wens@...e.org>,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: mv64xxx: remove unreachable signal case handling

On Thu, Jun 11, 2015 at 05:27:33PM +0200, Nicholas Mc Guire wrote:
> 'commit d295a86eab20 ("i2c: mv64xxx: work around signals causing I2C
> transactions to be aborted")' removed the wait_event_interruptible_timeout 
> to prevent half/mixed i2c messages from being sent/received but forgot to
> drop the signal received cases in the return handling. This just removes
> this dead code and simplifies the error message as "time_left" only can be 
> 0 here and thus it conveys no additional information.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> ---
> 
> Patch was compile tested with multi_v7_defconfig 
> (implies CONFIG_I2C_MV64XXX=y)
> 
> Patch is against 4.1-rc7 (localversion-next is -next-20150611)

Hmm, IMO this patch is too intrusive to be applied without actual
testing.

> 
>  drivers/i2c/busses/i2c-mv64xxx.c |   15 +++------------
>  1 file changed, 3 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
> index 30059c1..a4f8ece 100644
> --- a/drivers/i2c/busses/i2c-mv64xxx.c
> +++ b/drivers/i2c/busses/i2c-mv64xxx.c
> @@ -534,7 +534,6 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
>  {
>  	long		time_left;
>  	unsigned long	flags;
> -	char		abort = 0;
>  
>  	time_left = wait_event_timeout(drv_data->waitq,
>  		!drv_data->block, drv_data->adapter.timeout);
> @@ -542,25 +541,17 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
>  	spin_lock_irqsave(&drv_data->lock, flags);
>  	if (!time_left) { /* Timed out */
>  		drv_data->rc = -ETIMEDOUT;
> -		abort = 1;
> -	} else if (time_left < 0) { /* Interrupted/Error */
> -		drv_data->rc = time_left; /* errno value */
> -		abort = 1;
> -	}
> -
> -	if (abort && drv_data->block) {
>  		drv_data->aborting = 1;
>  		spin_unlock_irqrestore(&drv_data->lock, flags);
>  
>  		time_left = wait_event_timeout(drv_data->waitq,
>  			!drv_data->block, drv_data->adapter.timeout);
>  
> -		if ((time_left <= 0) && drv_data->block) {

I am especially unsure about the drv_data->block removal. Did you double
check if we can do this?

> +		if (time_left == 0) {
>  			drv_data->state = MV64XXX_I2C_STATE_IDLE;
>  			dev_err(&drv_data->adapter.dev,
> -				"mv64xxx: I2C bus locked, block: %d, "
> -				"time_left: %d\n", drv_data->block,
> -				(int)time_left);
> +				"mv64xxx: I2C bus locked, block: %d\n",
> +				drv_data->block);

And if so, shouldn't that also be always 1 in the output here?

>  			mv64xxx_i2c_hw_init(drv_data);
>  		}
>  	} else

Maybe (not sure) it also helps to split the patch into everything
dealing with time_left as patch 1) and simplifying by drv_data->block
removal as patch2?

Thanks,

   Wolfram


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