Re: [PATCH v21] PCI: Avoid D3 at suspend for AMD PCIe root ports w/ USB4 controllers

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Mon, Oct 02, 2023 at 01:09:06PM -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 # 6.1.y: 70b70a4: PCI/sysfs: Protect driver's D3cold preference from user space
> Cc: stable@vger.kernel.org # 6.5.y: 70b70a4: PCI/sysfs: Protect driver's D3cold preference from user space
> Cc: stable@vger.kernel.org # 6.6.y: 70b70a4: PCI/sysfs: Protect driver's D3cold preference from user space
> 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>

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>