Re: [PATCH] i2c: samsung: resume race fix

[Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>]

On Wed, 07 Nov 2012 15:58:26 +0530, Naveen Krishna Chatradhi wrote:
> Don't unmark the device as suspended until after it's been re-setup.
> 
> The main race would be w.r.t. an i2c driver that gets resumed at the same
> time (asyncronously), that is allowed to do a transfer since suspended
> is set to 0 before reinit, but really should have seen the -EIO return
> instead.

I thought that the suspend order was children first and the resume
order was parent first?

If this can really happen then I am afraid this is an issue for more
than just i2c-s3c2410. The proposed solution is also not really
satisfactory, as the i2c client will certainly still fail to resume
properly (the only improvement is that now the failure is no longer
silent.)

> 
> Signed-off-by: Olof Johansson <olofj-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-s3c2410.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
> index 3e0335f..dbaf920 100644
> --- a/drivers/i2c/busses/i2c-s3c2410.c
> +++ b/drivers/i2c/busses/i2c-s3c2410.c
> @@ -1134,10 +1134,10 @@ static int s3c24xx_i2c_resume(struct device *dev)
>  	struct platform_device *pdev = to_platform_device(dev);
>  	struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);
>  
> -	i2c->suspended = 0;
>  	clk_prepare_enable(i2c->clk);
>  	s3c24xx_i2c_init(i2c);
>  	clk_disable_unprepare(i2c->clk);
> +	i2c->suspended = 0;
>  
>  	return 0;
>  }

Acked-by: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>

(Not perfect but still better than before.)

-- 
Jean Delvare