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

[Rafael J. Wysocki]

On Thu, Apr 7, 2022 at 5:49 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>
> 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: https://lore.kernel.org/linux-pm/11967527.O9o76ZdvQC@kreacher
> > 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>
>
> Applied with Mika's reviewed-by to pci/pm for v5.19, thanks!

This doesn't compile when CONFIG_PM_SLEEP in uset, sorry about this.

I'll send a v2, but if you prefer an incremental fix, please let me know.

>
> > ---
> >  drivers/pci/pci-driver.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > Index: linux-pm/drivers/pci/pci-driver.c
> > ===================================================================
> > --- linux-pm.orig/drivers/pci/pci-driver.c
> > +++ linux-pm/drivers/pci/pci-driver.c
> > @@ -1312,7 +1312,7 @@ static int pci_pm_runtime_resume(struct
> >        * to a driver because although we left it in D0, it may have gone to
> >        * D3cold when the bridge above it runtime suspended.
> >        */
> > -     pci_restore_standard_config(pci_dev);
> > +     pci_pm_default_resume_early(pci_dev);
> >
> >       if (!pci_dev->driver)
> >               return 0;
> >
> >
> >