Re: [PATCH] PCI/ASPM: Should not report ASPM support to BIOS if FADT indicates ASPM is unsupported

Bjorn Helgaas
2022-07-13T18:29:01Z

[+cc Kai-Heng, Vidya, who also have ASPM patches in flight]

On Wed, Jul 13, 2022 at 07:26:12PM +0800, Manyi Li wrote:
> Startup log of ASUSTeK X456UJ Notebook show:
> [ 0.130563] ACPI FADT declares the system doesn't support PCIe ASPM, so disable it
> [ 48.092472] pcieport 0000:00:1c.5: PCIe Bus Error: severity=Corrected, type=Physical Layer, (Receiver ID)
> [ 48.092479] pcieport 0000:00:1c.5: device [8086:9d15] error status/mask=00000001/00002000
> [ 48.092481] pcieport 0000:00:1c.5: [ 0] RxErr
> [ 48.092490] pcieport 0000:00:1c.5: AER: Corrected error received: 0000:00:1c.5
> [ 48.092504] pcieport 0000:00:1c.5: AER: can't find device of ID00e5
> [ 48.092506] pcieport 0000:00:1c.5: AER: Corrected error received: 0000:00:1c.5

Can you elaborate on the connection between the FADT ASPM bit and the
AER logs above?

What problem are we solving here? A single corrected error being
logged? An infinite stream of errors? A device that doesn't work at
all?

We don't need the dmesg timestamps unless they contribute to
understanding the problem. I don't think they do in this case.

> Signed-off-by: Manyi Li <limanyi@uniontech.com>
> ---
> drivers/pci/pcie/aspm.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index a96b7424c9bc..b173d3c75ae7 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -1359,6 +1359,7 @@ void pcie_no_aspm(void)
> if (!aspm_force) {
> aspm_policy = POLICY_DEFAULT;
> aspm_disabled = 1;
> + aspm_support_enabled = false;

This makes pcie_no_aspm() work the same as booting with
"pcie_aspm=off". That might be reasonable.

I do wonder why we need both "aspm_disabled" and
"aspm_support_enabled". And I wonder why we need to set "aspm_policy"
when we're disabling ASPM. But those aren't really connected to your
change here.

> }
> }
>
> --
> 2.20.1
>
>
>