[AMD Public Use]

> -----Original Message-----
> From: Lukas Wunner <[email protected]>
> Sent: Friday, October 2, 2020 1:10 AM
> To: Bjorn Helgaas <[email protected]>; Rafael J. Wysocki
> <[email protected]>; Len Brown <[email protected]>
> Cc: Deucher, Alexander <[email protected]>; Mika Westerberg
> <[email protected]>; [email protected]; linux-
> [email protected]; [email protected]; Arthur Borsboom
> <[email protected]>; matoro <[email protected]>; Aaron
> Zakhrov <[email protected]>; Michal Rostecki
> <[email protected]>; Shai Coleman <[email protected]>
> Subject: [PATCH] PCI/ACPI: Whitelist hotplug ports for D3 if power managed
> by ACPI
> 
> Recent laptops with dual AMD GPUs fail to suspend the discrete GPU, thus
> causing lockups on system sleep and high power consumption at runtime.
> The discrete GPU would normally be suspended to D3cold by turning off
> ACPI _PR3 Power Resources of the Root Port above the GPU.
> 
> However on affected systems, the Root Port is hotplug-capable and
> pci_bridge_d3_possible() only allows hotplug ports to go to D3 if they belong
> to a Thunderbolt device or if the Root Port possesses a
> "HotPlugSupportInD3" ACPI property.  Neither is the case on affected
> laptops.  The reason for whitelisting only specific, known to work hotplug
> ports for D3 is that there have been reports of SkyLake Xeon-SP systems
> raising Hardware Error NMIs upon suspending their hotplug ports:
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.
> kernel.org%2Flinux-pci%2F20170503180426.GA4058%40otc-nc-
> 03%2F&amp;data=02%7C01%7Calexander.deucher%40amd.com%7C712c82d
> abd82477e540408d8669172c3%7C3dd8961fe4884e608e11a82d994e183d%7C0
> %7C0%7C637372123238938344&amp;sdata=S1%2ByqWpkuZcilrl7kRXQyodrN
> P66MAjcECRDd7tEjpE%3D&amp;reserved=0
> 
> But if a hotplug port is power manageable by ACPI (as can be detected
> through presence of Power Resources and corresponding _PS0 and _PS3
> methods) then it ought to be safe to suspend it to D3.  To this end, amend
> acpi_pci_bridge_d3() to whitelist such ports for D3.
> 
> Link:
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitla
> b.freedesktop.org%2Fdrm%2Famd%2F-
> %2Fissues%2F1222&amp;data=02%7C01%7Calexander.deucher%40amd.com
> %7C712c82dabd82477e540408d8669172c3%7C3dd8961fe4884e608e11a82d99
> 4e183d%7C0%7C0%7C637372123238938344&amp;sdata=k%2FRI8kSJclwhzYuc
> WSjAZNzNEaaU9JgIYNjJsV0dAWo%3D&amp;reserved=0
> Link:
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitla
> b.freedesktop.org%2Fdrm%2Famd%2F-
> %2Fissues%2F1252&amp;data=02%7C01%7Calexander.deucher%40amd.com
> %7C712c82dabd82477e540408d8669172c3%7C3dd8961fe4884e608e11a82d99
> 4e183d%7C0%7C0%7C637372123238938344&amp;sdata=JvakgHaQNI6XMaM
> eTHqtPJ5ooZP83lN%2F6wcdHyt53yA%3D&amp;reserved=0
> Link:
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitla
> b.freedesktop.org%2Fdrm%2Famd%2F-
> %2Fissues%2F1304&amp;data=02%7C01%7Calexander.deucher%40amd.com
> %7C712c82dabd82477e540408d8669172c3%7C3dd8961fe4884e608e11a82d99
> 4e183d%7C0%7C0%7C637372123238938344&amp;sdata=8clLa%2BCnwH4xtK
> Dc7F9%2FqPBSMFygpjP8EiPgVIz9LiE%3D&amp;reserved=0
> Reported-and-tested-by: Arthur Borsboom <[email protected]>
> Reported-and-tested-by: matoro <[email protected]>
> Reported-by: Aaron Zakhrov <[email protected]>
> Reported-by: Michal Rostecki <[email protected]>
> Reported-by: Shai Coleman <[email protected]>
> Signed-off-by: Lukas Wunner <[email protected]>
> Cc: [email protected]
> Cc: Alex Deucher <[email protected]>
> Cc: Rafael J. Wysocki <[email protected]>
> Cc: Mika Westerberg <[email protected]>

Thanks for sorting this out.
Acked-by: Alex Deucher <[email protected]>

> ---
>  drivers/pci/pci-acpi.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index
> d5869a0..d9aa551 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -944,6 +944,16 @@ static bool acpi_pci_bridge_d3(struct pci_dev *dev)
>       if (!dev->is_hotplug_bridge)
>               return false;
> 
> +     /* Assume D3 support if the bridge is power-manageable by ACPI. */
> +     adev = ACPI_COMPANION(&dev->dev);
> +     if (!adev && !pci_dev_is_added(dev)) {
> +             adev = acpi_pci_find_companion(&dev->dev);
> +             ACPI_COMPANION_SET(&dev->dev, adev);
> +     }
> +
> +     if (adev && acpi_device_power_manageable(adev))
> +             return true;
> +
>       /*
>        * Look for a special _DSD property for the root port and if it
>        * is set we know the hierarchy behind it supports D3 just fine.
> --
> 2.27.0
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