Re: [PATCH 1/2] PCI/PM: Disable bridge D3 on Lenovo ThinkCentre M90n-1

[Rafael J. Wysocki (Intel)]

On Mon, Nov 2, 2026 at 2:57 PM Mario Limonciello <superm1@xxxxxxxxxx> wrote:
>
> On the Lenovo ThinkCentre M90n-1 (board 314D), suspending the empty
> Root Port 9 turns off a clock needed by the onboard RTL8168 behind
> Root Port 12.  The NIC becomes inaccessible and r8169 fails to probe
> with "Unable to change power state from D3cold to D0".
>
> The RP09.PXP_._OFF method gates PCH SRC clock 1, which also supplies
> the NIC behind Root Port 12.  Keeping Root Port 9 in D0 preserves
> that clock and allows the NIC to probe.  Commit 4d4c10f763d7 ("PCI:
> Explicitly put devices into D0 when initializing") exposed the firmware
> bug on every boot by ensuring that the first runtime suspend executes
> the power resource's _OFF method.
>
> Add the board to bridge_d3_blacklist to prevent bridge D3 transitions.
> Check the blacklist before platform_pci_bridge_d3(), since ACPI allows
> D3 on the affected hotplug port and would otherwise bypass the quirk.
>
> Fixes: 4d4c10f763d7 ("PCI: Explicitly put devices into D0 when initializing")
> Reported-by: Joshua Perry <josh@xxxxxxxx>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=222179
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Mario Limonciello <superm1@xxxxxxxxxx>

As per the discussion in the bug entry

Reviewed-by: Rafael J. Wysocki (Intel) <rafael@xxxxxxxxxx>

> ---
>  drivers/pci/pci.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 7c6f2aba81443..17ec7f065682d 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -3028,6 +3028,17 @@ static const struct dmi_system_id bridge_d3_blacklist[] = {
>                         DMI_MATCH(DMI_BOARD_VERSION, "95.33"),
>                 },
>         },
> +       {
> +               /*
> +                * Suspending Root Port 9 gates a clock used by the onboard
> +                * RTL8168 behind Root Port 12, making the NIC inaccessible.
> +                */
> +               .ident = "Lenovo ThinkCentre M90n-1",
> +               .matches = {
> +                       DMI_MATCH(DMI_BOARD_VENDOR, "LENOVO"),
> +                       DMI_MATCH(DMI_BOARD_NAME, "314D"),
> +               },
> +       },
>  #endif
>         { }
>  };
> @@ -3073,6 +3084,10 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
>                 if (bridge->is_thunderbolt)
>                         return true;
>
> +               /* Firmware D3 support does not override known platform bugs. */
> +               if (dmi_check_system(bridge_d3_blacklist))
> +                       return false;
> +
>                 /* Platform might know better if the bridge supports D3 */
>                 if (platform_pci_bridge_d3(bridge))
>                         return true;
> @@ -3085,9 +3100,6 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
>                 if (IS_ENABLED(CONFIG_X86) && bridge->is_pciehp)
>                         return false;
>
> -               if (dmi_check_system(bridge_d3_blacklist))
> -                       return false;
> -
>                 /*
>                  * Out of caution, we only allow PCIe ports from 2015 or newer
>                  * into D3 on x86.
>
> --
> 2.53.0
>