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.
> 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.
>
> - 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
>
