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 21, 2016 6:43 AM
> To: Deucher, Alexander
> Cc: amd-gfx at lists.freedesktop.org; Zhang, Hawking; Koenig, Christian; dri-
> devel at lists.freedesktop.org; Christoph Haag
> Subject: ATPX changes in drm-next-4.8 and D3cold handling
> 
> Hi Alex,
> 
> There are a couple of changes for 4.8 that try to detect whether the
> "power_cntl" flag is present. Originally attributed to a firmware bug,
> it seems that the detection is performed too late resulting in flags
> that are always zero
> (https://bugzilla.kernel.org/show_bug.cgi?id=115321).  What PX platform
> are these patches tested with, did they have the same issue?
> 
> 
> 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?

> 
> With these changes, the nouveau driver had to disable use of the _DSM
> ACPI method (comparable to ATPX), otherwise both interfaces are used
> which could cause issues like being unable to resume the device.
> Also note that pcieport currently only handles D3cold for devices with a
> BIOS date in 2015 (or newer), you need to detect this with an approach
> like http://www.spinics.net/lists/linux-pci/msg52602.html
> 

My latest PX patches should handle this correctly.  We have flags in the ATPX interface to know what sort of system we are.  See:
https://cgit.freedesktop.org/~agd5f/linux/commit/?h=drm-next-4.8&id=b8c9fd5ad4b478ec1a5482177833e1a7082e48bd
https://cgit.freedesktop.org/~agd5f/linux/commit/?h=drm-next-4.8&id=31764c1e3b2bd6e9c8eaea1318a215afb6a8bad9
https://cgit.freedesktop.org/~agd5f/linux/commit/?h=drm-next-4.8&id=8491999285a3e5a5395ac87098bb1f26c465b62b

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


> We also found that the Nvidia HDMI audio device (function 1) would
> prevent the pcieport from sleeping. For modern Nvidia hardware this is
> apparently not an issue because these somehow hide the audio device, but
> it might be an issue for AMD hardware. See also
> https://lists.freedesktop.org/archives/dri-devel/2016-July/112759.html

Thanks for the heads up.

Alex

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