On Thu, Nov 09, 2017 at 02:37:40PM -0800, Tony Lindgren wrote:
> * Ladislav Michl <ladis@xxxxxxxxxxxxxx> [171109 22:33]:
> > On Thu, Nov 09, 2017 at 01:57:07PM -0800, Tony Lindgren wrote:
> > > Maybe you can block idle states from your driver with PM QoS?
> > >
> > > Just add some latency requirement. See for example what was done
> > > earlier for omap3 audio in commit 9834ffd1ecc3 ("ASoC: omap-mcbsp: Add PM
> > > QoS support for McBSP to prevent glitches").
> > >
> > > Not sure if we can do this in a generic way.. But maybe it's doable for
> > > things like PWM drivers.
> >
> > That seems to be rather problematic as I need this for generic driver:
> > drivers/media/rc/gpio-ir-recv.c
> > I need to be able to detect key presses of various remotes, so protocol
> > is unknown in advance. Having such a big jitter leads to false positives
> > when guessing protocol or decoding errors.
> >
> > I was also considering using FIQ handler, but it probably won't help in
> > this case.
>
> Hmm to me it seems that PM QoS would be totally justified for a driver
I will give it a try...
> like that. But actually, why don't you use drivers/pwm/pwm-omap-dmtimer.c
> like drivers/media/rc/ir-rx51.c is doing? Then you have the dmtimer
> driving things..
That would be excelent choice, of course, but IGEPv2 board does not route
any pwm capable pin on its pin header. Also note I need another direction,
while ir-rx51 is transmitter driver, gpio-ir-recv is a receiver. I didn't
check whenever dm timer is input capture ready.
Btw, ir-rx51 could be probably replaced with generic driver, one day
https://git.linuxtv.org/media_tree.git/tree/drivers/media/rc/pwm-ir-tx.c
Best regards,
ladis
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