On Thu, Apr 26, 2018 at 02:10:23PM +0200, Hans de Goede wrote: > On some devices the contents of the ctrl register get lost over a > suspend/resume and the PWM comes back up disabled after the resume. > > This is seen on some Bay Trail devices with the PWM in ACPI enumerated > mode, so it shows up as a platform device instead of a PCI device. > > If we still think it is enabled and then try to change the duty-cycle > after this, we end up with a "PWM_SW_UPDATE was not cleared" error and > the PWM is stuck in that state from then on. > > This commit adds suspend and resume pm callbacks to the pwm-lpss-platform > code, which save/restore the ctrl register over a suspend/resume, fixing > this. > > Note that: > > 1) There is no need to do this over a runtime suspend, since we > only runtime suspend when disabled and then we properly set the enable > bit and reprogram the timings when we re-enable the PWM. > > 2) This may be happening on more systems then we realize, but has been > covered up sofar by a bug in the acpi-lpss.c code which was save/restoring > the regular device registers instead of the lpss private registers due to > lpss_device_desc.prv_offset not being set. This is fixed by a later patch > in this series. > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > --- > Changes in v2: > -Add Cc: stable@xxxxxxxxxxxxxxx to make sure this goes into stable > together with "ACPI / LPSS: Add missing prv_offset setting for byt/cht > PWM devices" which depends on this > --- > drivers/pwm/pwm-lpss-platform.c | 5 +++++ > drivers/pwm/pwm-lpss.c | 30 ++++++++++++++++++++++++++++++ > drivers/pwm/pwm-lpss.h | 2 ++ > 3 files changed, 37 insertions(+) Applied, thanks. Thierry
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