ATPX changes in drm-next-4.8 and D3cold handling

[Deucher, Alexander]

> -----Original Message-----
> From: Peter Wu [mailto:peter at lekensteyn.nl]
> Sent: Thursday, July 28, 2016 8:00 PM
> To: Lukas Wunner
> Cc: Deucher, Alexander; dri-devel at lists.freedesktop.org; Christoph Haag;
> Koenig, Christian; amd-gfx at lists.freedesktop.org; Zhang, Hawking
> Subject: Re: ATPX changes in drm-next-4.8 and D3cold handling
> 
> On Thu, Jul 28, 2016 at 05:40:31PM +0200, Lukas Wunner wrote:
> > On Thu, Jul 28, 2016 at 03:33:25PM +0000, Deucher, Alexander wrote:
> > > > From: Peter Wu [mailto:peter at lekensteyn.nl]
> > > > Sent: Thursday, July 21, 2016 6:43 AM
> > > > In case you missed it, Dave's D3cold patches were succeeded by
> changes
> > > > in PCI core. Relevant commits in the pci/pm branch:
> > > >
> > > >     006d44e PCI: Add runtime PM support for PCIe ports
> > > >     16468c7 ACPI / hotplug / PCI: Runtime resume bridge before rescan
> > > >     d963f65 PCI: Power on bridges before scanning new devices
> > > >     9d26d3a PCI: Put PCIe ports into D3 during suspend
> > > >     43f7f88 PCI: Don't clear d3cold_allowed for PCIe ports
> > >
> > > Did those get merged yet?
> >
> > They will go into 4.8. Should have gone into 4.7 already but were
> > dropped at the last minute.
> >
> >
> > > I just need to revert this commit once the d3cold patches land:
> > > https://cgit.freedesktop.org/~agd5f/linux/commit/?h=drm-next-
> 4.8&id=bdfb76040068d960cb9e226876be8a508d741c4a
> >
> > So you probably need to revert this now.
> >
> > Best regards,
> > Lukas
> 
> It is better to revert it before the PCI/PM patches get merged,
> otherwise you risk that the device is already put in D3 before the
> bridge tries to do it again. This is currently happening with nouveau on
> -next.
> 
> Do these AMD hw exist on BIOSes pre-2015? Currently the D3cold work in
> the PCI/PM branch only enable the D3cold handling via the bridge when
> the BIOS is >= 2015.

Systems designed for windows 10 use d3 cold rather than the legacy interfaces.  Setting the ACPI OSI to windows10 will enable d3cold, setting it to a previous version of windows will use the old method.  At least on AMD PX systems there is a bit in the ATPX information block that indicates the current setting hybrid graphics (aka d3cold) or the ATPX power control for dGPU power control.

Alex

> --
> Kind regards,
> Peter Wu
> https://lekensteyn.nl