Re: [PATCH] PCI/PM: Put devices to low power state on shutdown

[Mario Limonciello <mario.limonciello@amd.com>]

On 7/12/2024 1:24, Kai-Heng Feng wrote:
> Some laptops wake up after poweroff when HP Thunderbolt Dock G4 is
> connected.
> 
> The following error message can be found during shutdown:
> pcieport 0000:00:1d.0: AER: Correctable error message received from 0000:09:04.0
> pcieport 0000:09:04.0: PCIe Bus Error: severity=Correctable, type=Data Link Layer, (Receiver ID)
> pcieport 0000:09:04.0:   device [8086:0b26] error status/mask=00000080/00002000
> pcieport 0000:09:04.0:    [ 7] BadDLLP
> 
> Calling aer_remove() during shutdown can quiesce the error message,
> however the spurious wakeup still happens.
> 
> The issue won't happen if the device is in D3 before system shutdown, so
> putting device to low power state before shutdown to solve the issue.
> 
> I don't have a sniffer so this is purely guesswork, however I believe
> putting device to low power state it's the right thing to do.
> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=219036
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

This is directionally very similar to the proposal that I had at the end 
of last year.

https://lore.kernel.org/linux-pci/20231213182656.6165-1-mario.limonciello@amd.com/#t

I definitely think we should be aiming at all devices that don't wake 
the system as being in D3 at shutdown.

> ---
>   drivers/pci/pci-driver.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index af2996d0d17f..4c6f66f3eb54 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -510,6 +510,14 @@ static void pci_device_shutdown(struct device *dev)
>   	if (drv && drv->shutdown)
>   		drv->shutdown(pci_dev);
>   
> +	/*
> +	 * If driver already changed device's power state, it can mean the
> +	 * wakeup setting is in place, or a workaround is used. Hence keep it
> +	 * as is.
> +	 */
> +	if (!kexec_in_progress && pci_dev->current_state == PCI_D0)
> +		pci_prepare_to_sleep(pci_dev);
> +
>   	/*
>   	 * If this is a kexec reboot, turn off Bus Master bit on the
>   	 * device to tell it to not continue to do DMA. Don't touch