Re: [PATCH v22] PCI: Avoid D3 at suspend for AMD PCIe root ports w/ USB4 controllers

[Bjorn Helgaas <helgaas@kernel.org>]

On Thu, Oct 05, 2023 at 08:47:30PM +0200, Lukas Wunner wrote:
> On Thu, Oct 05, 2023 at 01:14:40PM -0500, Bjorn Helgaas wrote:
> > On Wed, Oct 04, 2023 at 09:49:59AM -0500, Mario Limonciello wrote:
> > > Iain reports that USB devices can't be used to wake a Lenovo Z13 from
> > > suspend.  This occurs because on some AMD platforms, even though the Root
> > > Ports advertise PME_Support for D3hot and D3cold, they don't handle PME
> > > messages and generate wakeup interrupts from those states when amd-pmc has
> > > put the platform in a hardware sleep state.
> > > 
> > > Iain reported this on an AMD Rembrandt platform, but it also affects
> > > Phoenix SoCs.  On Iain's system, a USB4 router below the affected Root Port
> > > generates the PME. To avoid this issue, disable D3 for the root port
> > > associated with USB4 controllers at suspend time.
> > > 
> > > Restore D3 support at resume so that it can be used by runtime suspend.
> > > The amd-pmc driver doesn't put the platform in a hardware sleep state for
> > > runtime suspend, so PMEs work as advertised.
> > > 
> > > Cc: stable@vger.kernel.org
> > > Link: https://learn.microsoft.com/en-us/windows-hardware/design/device-experiences/platform-design-for-modern-standby#low-power-core-silicon-cpu-soc-dram [1]
> > > Fixes: 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend")
> > > Reported-by: Iain Lane <iain@orangesquash.org.uk>
> > > Closes: https://forums.lenovo.com/t5/Ubuntu/Z13-can-t-resume-from-suspend-with-external-USB-keyboard/m-p/5217121
> > > Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> > 
> > Applied to pci/pm for v6.7, thanks for all your patience!
> 
> One belated thought I have on this is that it might be a better fit in
> arch/x86/pci/fixups.c rather than drivers/pci/quirks.c.

Good point, I moved it there, thanks.  There are lots of other things
that should probably be moved, but no point in adding more.

Bjorn