Re: [PATCH v2] iio: adc: exynos_adc: Handle timeout issues

[Tomasz Figa <tomasz.figa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Thursday 02 of May 2013 11:22:27 Naveen Krishna Ch wrote:
> On 2 May 2013 11:10, Tomasz Figa <tomasz.figa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > Hi Naveen,
> > 
> > On Thursday 02 of May 2013 11:01:03 Naveen Krishna Chatradhi wrote:
> >> From: Naveen Krishna Chatradhi <ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> >> 
> >> This patch does the following
> >> 1. use wait_for_completion_timeout instead of
> >> 
> >>    wait_for_completion_interruptible_timeout
> >> 
> >> 2. Reset software if a timeout happens.
> >> 3. Also reduce the timeout to 100milli secs
> > 
> > I wonder what this patch is trying to fix. In what conditions can an
> > ADC conversion time out?
> > 
> > Sorry if it was already explained in discussion. Still, I think that
> > commit message of a patch should explain why it is needed.
> 
> The discussion started with a bug reported by Dan Carpenter
> http://www.gossamer-threads.com/lists/linux/kernel/1693284?page=last
> 
> and during the discussion we found out the return cases of
> wait_for_completion_interruptible_timeout() were not handled properly.
> so we implemented hw_reset during the error cases.
> 
> As such ISR only does a regiser access.  Which may never timeout.
> This patch reduces the timeout and removes the use of interruptible.
> As, ADC's ISR would be too fast to handle the interruptible operation.
> 
> Now i see, there is nothing much this driver is fixing.
> As you suggest, the subject can be little less harsh.

OK, thanks for the explanation.

Best regards,
Tomasz