Re: [PATCH 2/2] pwm: lpss: Check PWM powerstate after resume on Cherry Trail devices

["Rafael J. Wysocki" <rafael@kernel.org>]

On Wed, Oct 10, 2018 at 1:14 PM Hans de Goede <hdegoede@redhat.com> wrote:
>
> Hi,
>
> On 06-10-18 16:16, Andy Shevchenko wrote:
> > On Sat, Oct 06, 2018 at 10:55:41AM +0200, Hans de Goede wrote:
> >> On 03-10-18 11:22, Rafael J. Wysocki wrote:
> >>> On Monday, September 24, 2018 11:40:14 AM CEST Hans de Goede wrote:
> >
> >>> Also, why don't you use acpi_device_get_power() instead of evaluating
> >>> _PSC directly?  It should make no difference if there are no power
> >>> resources, should it?
> >
> >> 2) acpi_device_get_power() is not exported to modules
> >
> > Do we have any side effects if we just export it?
> > I would think exporting is better than open coding.
>
> acpi_device_get_power() does a lot more then just call the _PSC
> method, while as explained we really just want the _PSC method
> as that checks the actual D3 bit which we are interested in.
>
> But as Rafael mentioned if the DSDT does not define power-resources
> (which in the 3 DSDTs I just checked it doesn't for the PWM node) then
> acpi_device_get_power() is equivalent.
>
> So I guess I could change this, but I would prefer to stick with
> the direct _PSC call.

And I would prefer acpi_device_get_power() to be used as long as it
works in this case.

I really don't want every driver to evaluate ACPI methods directly at will.

Thanks,
Rafael