lkml.org 
[lkml]   [2020]   [Mar]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 4/6] pwm: omap-dmtimer: Fix pwm disabling sequence
* Lokesh Vutla <lokeshvutla@ti.com> [200228 09:58]:
> pwm_omap_dmtimer_disable() calls .stop callback which abruptly stops the
> timer counter. This doesn't complete the current pwm cycle and
> immediately disables the pwm. Instead disable the auto reload
> functionality which allows to complete the current pwm cycle and then
> disables the timer.
>
> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
> ---
> drivers/pwm/pwm-omap-dmtimer.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c
> index bc338619232d..89b3c25d02b8 100644
> --- a/drivers/pwm/pwm-omap-dmtimer.c
> +++ b/drivers/pwm/pwm-omap-dmtimer.c
> @@ -93,8 +93,16 @@ static void pwm_omap_dmtimer_disable(struct pwm_chip *chip,
> {
> struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
>
> + /*
> + * Disable auto reload so that the current cycle gets completed and
> + * then the counter stops.
> + */
> mutex_lock(&omap->mutex);
> - omap->pdata->stop(omap->dm_timer);
> + omap->pdata->set_pwm(omap->dm_timer,
> + pwm_get_polarity(pwm) == PWM_POLARITY_INVERSED,
> + true, OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE,
> + false);
> +
> mutex_unlock(&omap->mutex);
> }

I'm seeing an issue with this patch where after use something is
left on and power consumption stays higher by about 30 mW after
use.

I can reproduce this easily on droid4 with Sebastian's rumble-test
app[0]. After use, I sometimes also hear the vibrator keep chirping
quietly, so there seems to be some pwm still happening after disable :)

Reloading modules for pwm-vibra and pwm-omap-dmtimer make the power
consumption go back down again.

If you have a scope set up, maybe check the lines are quiet after
disable after this patch?

Regards,

Tony


[0] https://git.collabora.com/cgit/user/sre/rumble-test.git/plain/rumble-test.c

\
 
 \ /
  Last update: 2020-03-06 19:15    [W:3.033 / U:3.520 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site