Re: [PATCH 2/2] clk: qcom: gcc-sc7280: Keep USB GDSC power domains on when USB wakeup is enabled

[Matthias Kaehlcke <mka@chromium.org>]

On Fri, Aug 26, 2022 at 03:12:05PM +0200, Johan Hovold wrote:
> On Fri, Aug 26, 2022 at 06:05:19AM -0700, Matthias Kaehlcke wrote:
> > On Thu, Aug 25, 2022 at 03:16:58PM -0700, Matthias Kaehlcke wrote:
> > > On Wed, Aug 24, 2022 at 10:47:44AM +0200, Johan Hovold wrote:
> 
> > > > The wakeup setting doesn't seem to have anything to do with the genpd
> > > > issues on sc8280xp and the controller doesn't resume properly regardless
> > > > of whether the PHYs have been disabled or not during suspend unless the
> > > > PD is left on.
> > > 
> > > I'm essentially seeing the same. USB is hosed after resume unless the PD
> > > is left on.
> > > 
> > > On Chrome OS we currently work around that with a version of commit
> > > d9be8d5c5b03 ("usb: dwc3: qcom: Keep power domain on to retain controller
> > > status") which was reverted upstream. I'm not sure whether USB worked after
> > > resume before we enabled wakeup support. I would have sworn it did, but we
> > > landed an old version of the wakeup patches a long time ago, so my
> > > memory might be failing me.
> > 
> > I need to remind myself that keeping the GDSC on is only needed when the PHYs
> > are kept on. The PHYs were always off before wakeup support was added, which
> > is why USB wasn't broken after suspend in the pre-wakeup days.
> 
> Ok, so to be clear: if you disable wakeup with my patches applied so
> that the PD is actually turned off, USB still resumes with only
> GENPD_FLAG_ACTIVE_WAKEUP set?
> 
> That is, you don't need to set ALWAYS_ON as I do with sc8280xp?

Correct

The USB controller isn't entirely happy:

[   23.062936] xhci-hcd xhci-hcd.13.auto: xHC error in resume, USBSTS 0x411, Reinit

but USB still works.