[PATCH 1/1][SRU][N] PCI: Explicitly put devices into D0 when initializing

[Thomas Lamprecht]

Am 29.05.25 um 03:15 schrieb AceLan Kao:
> From: Mario Limonciello <mario.limonciello at amd.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/2110090
> 
> AMD BIOS team has root caused an issue that NVMe storage failed to come
> back from suspend to a lack of a call to _REG when NVMe device was probed.
> 
> 112a7f9c8edbf ("PCI/ACPI: Call _REG when transitioning D-states") added
> support for calling _REG when transitioning D-states, but this only works
> if the device actually "transitions" D-states.
> 
> 967577b062417 ("PCI/PM: Keep runtime PM enabled for unbound PCI devices")
> added support for runtime PM on PCI devices, but never actually
> 'explicitly' sets the device to D0.
> 
> To make sure that devices are in D0 and that platform methods such as
> _REG are called, explicitly set all devices into D0 during initialization.
> 
> Fixes: 967577b062417 ("PCI/PM: Keep runtime PM enabled for unbound PCI devices")
> Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
> Tested-by: Denis Benato <benato.denis96 at gmail.com>
> Tested-By: Yijun Shen <Yijun_Shen at Dell.com>
> Tested-By: David Perry <david.perry at amd.com>
> Reviewed-by: Rafael J. Wysocki <rafael at kernel.org>
> Link: https://patch.msgid.link/20250424043232.1848107-1-superm1@kernel.org
> (cherry picked from commit 4d4c10f763d7808fbade28d83d237411603bca05)
> Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao at canonical.com>

FYI: This causes regressions on PCI passthrough to QEMU/KVM, among other
things. A colleague found that the following patch on top fixes it here:

https://lore.kernel.org/all/20250611233117.61810-1-superm1@kernel.org/

Same holds for the Plucky backport in patch mail id:
<20250529010730.1863186-2-acelan.kao at canonical.com>