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

Mario Limonciello
2023-12-13T18:42:22Z

On 12/13/2023 12:38, Rafael J. Wysocki wrote:
> On Wed, Dec 13, 2023 at 7:27 PM Mario Limonciello
> <mario.limonciello@amd.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.

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@squebb.ca
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.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?
>

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

>> pcie_port_device_remove(dev);
>> --