Re: [PATCH] pwm: imx: don't reprogram PWMSAR if PWM is disabled

[Thierry Reding <thierry.reding@gmail.com>]

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On Tue, Aug 05, 2014 at 04:48:41PM +0800, Liu Ying wrote:
> On 08/05/2014 09:36 AM, Shawn Guo wrote:
> >On Fri, Aug 01, 2014 at 10:02:17PM +0400, Dmitry Eremin-Solenikov wrote:
> >>On Wed, Jul 23, 2014 at 12:09 PM, Dmitry Eremin-Solenikov
> >><dbaryshkov@gmail.com> wrote:
> >>>From: Dmitry Eremin-Solenikov <dmitry_eremin@mentor.com>
> >>>
> >>>Writing several values to PWMSAR register with PWM being disabled can
> >>>lead to FIFO (connected to PWMSAR) being overflown. Then after enabling
> >>>PWM, hardware will use stale values. Instead cache the duty cycles and
> >>>write them to the hardware only before enabling PWM.
> >>
> >>What about this patch?
> >
> >Copy Liu Ying who seems to have a patch [1] addressing the same problem?
> >
> 
> Yes, my patch may address the same problem. And, my patch may cache the last
> duty cycle as well when the PWM is disabled. The difference is that my patch
> caches it in the register PWMSAR instead of a variable.

Dmitry,

I've just pushed Liu's patch that might fix this problem. Can you give
it a quick spin to see if it fixes the issue that you're seeing? It's in
the for-next branch of the PWM tree[0].

Thanks,
Thierry

[0]: git://git.kernel.org/pub/scm/linux/kernel/git/thierry.reding/linux-pwm.git

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