On Wed, Oct 27, 2021 at 12:53 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > On Tue, Oct 26, 2021 at 10:28:38AM +0800, Kai-Heng Feng wrote: > > > What if we fallback to the original approach and use the VMD driver > > to enable ASPM and LTR values? At least I think Intel should be > > able to provide correct values for their SoC. > > Can you post the patches for that? I'm not sure exactly what the > original approach was. Are these the same as the downstream support > you mention below? This is the previous attempt to enable VMD ASPM: https://lore.kernel.org/linux-pci/20200930082455.25613-1-kai.heng.feng@xxxxxxxxxxxxx/ It didn't enable LTR though. Right now the downstream kernel use PCI quirk to enable VMD ASPM and LTR: https://kernel.ubuntu.com/git/ubuntu/unstable.git/commit/?id=069ab00c2613d27cb7cdeb2a4c751de89dab81b4 https://kernel.ubuntu.com/git/ubuntu/unstable.git/commit/?id=1e4dec5fe846f8dd8954b173434670f8ae30b5ff The patches don't touch VMD driver to minimize merge conflict on VMD driver. I really hope we can put these changes to upstream VMD driver. Kai-Heng > > > So what other options do we have if we want to enable VMD ASPM while > > keeping CONFIG_PCIEASPM_DEFAULT=y? Right now we enabled the VMD > > ASPM/LTR bits in downstream kernel, but other distro users may want > > to have upstream support for this.
