Messages in this thread | | | Date | Wed, 22 Apr 2020 10:40:11 +0200 | From | Pascal Roeleven <> | Subject | Re: [linux-sunxi] [RFC PATCH 4/4] pwm: sun4i: Delay after writing the period |
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On 2020-04-22 05:43, Samuel Holland wrote: > Hello Pascal, > > On 3/17/20 10:59 AM, Pascal Roeleven wrote: >> When disabling, ensure the period write is complete before continuing. >> This fixes an issue on some devices when the write isn't complete >> before >> the panel is turned off but the clock gate is still on. >> >> Signed-off-by: Pascal Roeleven <dev@pascalroeleven.nl> >> --- >> drivers/pwm/pwm-sun4i.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c >> index a11d00f96..75250fd4c 100644 >> --- a/drivers/pwm/pwm-sun4i.c >> +++ b/drivers/pwm/pwm-sun4i.c >> @@ -299,6 +299,10 @@ static int sun4i_pwm_apply(struct pwm_chip *chip, >> struct pwm_device *pwm, >> sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm)); >> next_period = jiffies + usecs_to_jiffies(cstate.period / 1000 + 1); >> >> + /* When disabling, make sure the period register is written first */ >> + if (!state->enabled && cstate.enabled) >> + sun4i_pwm_wait(next_period); >> + > > It is not visible from the context of this patch, but this call to > sun4i_pwm_wait() ends up calling msleep() inside a spinlock, which > isn't > allowed. The spinlock should probably be converted to a mutex, > considering that > sun4i_pwm_apply() already sleeps and takes mutexes. > > Regards, > Samuel >
Yes you're right. A different implementation of this patch series is being worked on, in which I'll take this into account. Unfortunately I have other things to work on at the moment, so it might take a while.
Regards, Pascal
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