Re: [PATCH v1] PCI: PM: Power up all devices during runtime resume

From: Mika Westerberg
Date: Thu Apr 07 2022 - 04:51:39 EST

On Wed, Apr 06, 2022 at 09:00:52PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Currently, endpoint devices may not be powered up entirely during
> runtime resume that follows a D3hot -> D0 transition of the parent
> bridge.
> Namely, even if the power state of an endpoint device, as indicated
> by its PCI_PM_CTRL register, is D0 after powering up its parent
> bridge, it may be still necessary to bring its ACPI companion into
> D0 and that should be done before accessing it. However, the current
> code assumes that reading the PCI_PM_CTRL register is sufficient to
> establish the endpoint device's power state, which may lead to
> problems.
> Address that by forcing a power-up of all PCI devices, including the
> platform firmware part of it, during runtime resume.
> Link:
> Fixes: 5775b843a619 ("PCI: Restore config space on runtime resume despite being unbound")
> Reported-by: Abhishek Sahu <abhsahu@xxxxxxxxxx>
> Tested-by: Abhishek Sahu <abhsahu@xxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>