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

Matthew Garrett
2022-07-14T05:02:08Z

On Thu, Jul 14, 2022 at 11:20:26AM +0800, Kai-Heng Feng wrote:

> According to commit 387d37577fdd ("PCI: Don't clear ASPM bits when the
> FADT declares it's unsupported"), the bit means "just use the ASPM

Yes, the assumption is that if the BIOS set up ASPM but FADT indicates
it's unsupported, just trust that the BIOS did the right thing and don't
interfere. It's been a long time, but when we were clearing the ASPM
bits in response to this FADT setting, a bunch of machines suddenly
started consuming a lot more power than when running Windows.