Re: [PATCH] PCI/ASPM: Clarify that pcie_aspm=off means leave ASPM untouched

From: David E. Box
Date: Wed May 01 2024 - 16:07:11 EST


On Mon, 2024-04-29 at 14:18 -0500, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>
> Previously we claimed "pcie_aspm=off" meant that ASPM would be disabled,
> which is wrong.
>
> Correct this to say that with "pcie_aspm=off", Linux doesn't touch any ASPM
> configuration at all.  ASPM may have been enabled by firmware, and that
> will be left unchanged.  See "aspm_support_enabled".
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

LGTM.

Reviewed-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx>

> ---
>  Documentation/admin-guide/kernel-parameters.txt | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index bb884c14b2f6..4bc281d6e8d3 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4590,9 +4590,10 @@
>                 norid           [S390] ignore the RID field and force use of
>                                 one PCI domain per PCI function
>  
> -       pcie_aspm=      [PCIE] Forcibly enable or disable PCIe Active State
> Power
> +       pcie_aspm=      [PCIE] Forcibly enable or ignore PCIe Active State
> Power
>                         Management.
> -               off     Disable ASPM.
> +               off     Don't touch ASPM configuration at all.  Leave any
> +                       configuration done by firmware unchanged.
>                 force   Enable ASPM even on devices that claim not to support
> it.
>                         WARNING: Forcing ASPM on may cause system lockups.
>