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:3.431 / U:0.668 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site