Re: [PATCH 1/2] Revert "xhci: Enable RPM on controllers that support low-power states"

[Basavaraj Natikar <bnatikar@amd.com>]

On 12/4/2023 7:52 PM, Mathias Nyman wrote:
> On 4.12.2023 12.49, Basavaraj Natikar wrote:
>>
>> On 12/4/2023 3:38 PM, Mathias Nyman wrote:
>>> This reverts commit a5d6264b638efeca35eff72177fd28d149e0764b.
>>>
>>> This patch was an attempt to solve issues seen when enabling runtime PM
>>> as default for all AMD 1.1 xHC hosts. see commit 4baf12181509
>>> ("xhci: Loosen RPM as default policy to cover for AMD xHC 1.1")
>>
>> AFAK, only 4baf12181509 commit has regression on AMD xHc 1.1 below is
>> not regression
>> patch and its unrelated to AMD xHC 1.1.
>>
>> Only [PATCH 2/2] Revert "xhci: Loosen RPM as default policy to cover
>> for AMD xHC 1.1"
>> alone in this series solves regression issues.
>>
>
> Patch a5d6264b638e ("xhci: Enable RPM on controllers that support
> low-power states")
> was originally not supposed to go to stable. It was added later as it
> solved some
> cases triggered by 4baf12181509 ("xhci: Loosen RPM as default policy
> to cover for AMD xHC 1.1")
> see:
> https://lore.kernel.org/linux-usb/5993222.lOV4Wx5bFT@natalenko.name/
>
> Turns out it wasn't enough.
>
> If we now revert 4baf12181509 "xhci: Loosen RPM as default policy to
> cover for AMD xHC 1.1"
> I still think it makes sense to also revert a5d6264b638e.
> Especially from the stable kernels.

Yes , a5d6264b638e still solves other issues if underlying hardware doesn't support RPM
if we revert a5d6264b638e on stable releases then new issues (not related to regression)
other than AMD xHC 1.1 controllers including xHC 1.2 will still exist on stable releases.
If revert then we can backport to stable release later if required.

Sure, will send a follow up patch to fix 4baf12181509 alone on mainline if revert on all releases.

>
> This way we roll back this whole issue to a known working state.

Sure, for at-least a5d6264b638e if not revert on mainline then will not resend the same patch.

Thanks,
--
Basavaraj

>
> Thanks
> Mathias