Re: [PATCH 2/2] PCI/portdrv: Place PCIe port hierarchy into D3cold at shutdown

[Mario Limonciello]

On 12/13/2023 12:38, Rafael J. Wysocki wrote:
> On Wed, Dec 13, 2023 at 7:27 PM Mario Limonciello
> <mario.limonciello@xxxxxxx> wrote:
> > When a system is being powered off it's important that PCIe ports
> > have been put into D3cold as there is no other software to turn
> > off the devices at S5.
> >
> > If PCIe ports are left in D0 then any GPIOs toggled by the ACPI
> > power resources may be left enabled and devices may consume excess
> > power.
>
> Isn't that a platform firmware issue?
>
> It is the responsibility of the platform firmware to properly put the
> platform into S5, including power removal from devices that are not
> armed for power-on.

The specific issues that triggered this series were tied to the PCIe 
ports for dGPUs.  There is a GPIO that is toggled by _ON or _OFF.

Windows calls _OFF as part of S5..

> > Cc: mpearson-lenovo@xxxxxxxxx
> > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> > ---
> >   drivers/pci/pcie/portdrv.c | 11 ++++++++---
> >   1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
> > index 14a4b89a3b83..08238680c481 100644
> > --- a/drivers/pci/pcie/portdrv.c
> > +++ b/drivers/pci/pcie/portdrv.c
> > @@ -734,9 +734,14 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
> >   static void pcie_portdrv_shutdown(struct pci_dev *dev)
> >   {
> >          if (pci_bridge_d3_possible(dev)) {
> > -               pm_runtime_forbid(&dev->dev);
> > -               pm_runtime_get_noresume(&dev->dev);
> > -               pm_runtime_dont_use_autosuspend(&dev->dev);
> > +               /* whole hierarchy goes into a low power state for S5 */
> > +               if (system_state == SYSTEM_POWER_OFF) {
> > +                       pci_set_power_state(dev, PCI_D3cold);
> > +               } else {
> > +                       pm_runtime_forbid(&dev->dev);
> > +                       pm_runtime_get_noresume(&dev->dev);
> > +                       pm_runtime_dont_use_autosuspend(&dev->dev);
> > +               }
> >          }
>
> Wouldn't it be better to remove power from the port after running the
> code below?

Yes; I think you're right.  I'll do some more testing with this.

> >          pcie_port_device_remove(dev);
> > --