On Tue, Aug 22, 2023 at 6:23 PM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
>
> On Tue, Aug 22, 2023 at 11:41 AM Feiyang Chen <chenfeiyang@xxxxxxxxxxx> wrote:
> >
> > If the pm_cap of the PCI device is unset, do not read the
> > PCI_PM_CTRL register in pci_set_full_power_state().
>
> So this is the case when the current state is already 0 and so
> pci_power_up() returns 0 even though dev->pm_cap is not set. This
> should be mentioned in the changelog.
>
OK.
> > Fixes: e200904b275c ("PCI/PM: Split pci_power_up()")
> > Signed-off-by: Feiyang Chen <chenfeiyang@xxxxxxxxxxx>
> > ---
> > drivers/pci/pci.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 60230da957e0..d6671cefcfa7 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -1305,8 +1305,10 @@ static int pci_set_full_power_state(struct pci_dev *dev)
> > if (ret < 0)
> > return ret;
>
> IMO it would be better to move the dev->current_state == PCI_D0 check
> from pci_power_up() to this place, that is
>
> if (ret < 0) {
> if (dev->current_state == PCI_D0)
> return 0;
>
> return ret;
> }
>
> because nothing more needs to be done below in that case.
>
OK.
> >
> > - pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
> > - dev->current_state = pmcsr & PCI_PM_CTRL_STATE_MASK;
> > + if (dev->pm_cap) {
> > + pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
> > + dev->current_state = pmcsr & PCI_PM_CTRL_STATE_MASK;
> > + }
> > if (dev->current_state != PCI_D0) {
> > pci_info_ratelimited(dev, "Refused to change power state from %s to D0\n",
> > pci_power_name(dev->current_state));
> > --
> > 2.39.3
> >
