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

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Date:   Wed, 13 Dec 2023 19:38:14 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mario Limonciello <mario.limonciello@....com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, mpearson-lenovo@...ebb.ca
Subject: Re: [PATCH 2/2] PCI/portdrv: Place PCIe port hierarchy into D3cold at shutdown

On Wed, Dec 13, 2023 at 7:27 PM Mario Limonciello
<mario.limonciello@....com> 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.

> Cc: mpearson-lenovo@...ebb.ca
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  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?

>         pcie_port_device_remove(dev);
> --