Jonas Dreßler <verdre@xxxxxxx> wrote: > The most recent firmware (15.68.19.p21) of the 88W8897 PCIe+USB card > reports a hardcoded LTR value to the system during initialization, > probably as an (unsuccessful) attempt of the developers to fix firmware > crashes. This LTR value prevents most of the Microsoft Surface devices > from entering deep powersaving states (either platform C-State 10 or > S0ix state), because the exit latency of that state would be higher than > what the card can tolerate. > > Turns out the card works just the same (including the firmware crashes) > no matter if that hardcoded LTR value is reported or not, so it's kind > of useless and only prevents us from saving power. > > To get rid of those hardcoded LTR requirements, it's possible to reset > the PCI bridge device after initializing the cards firmware. I'm not > exactly sure why that works, maybe the power management subsystem of the > PCH resets its stored LTR values when doing a function level reset of > the bridge device. Doing the reset once after starting the wifi firmware > works very well, probably because the firmware only reports that LTR > value a single time during firmware startup. > > Signed-off-by: Jonas Dreßler <verdre@xxxxxxx> I'm not sure what was the conclusion from the discussion, so dropping the patch. Please resend once it's ready to be applied. Patch set to Changes Requested. -- https://patchwork.kernel.org/project/linux-wireless/patch/20211011134238.16551-1-verdre@xxxxxxx/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
