Re: [PATCH 6/6] drm/msm/a6xx: Limit GXPD votes to recovery in A8x

[Konrad Dybcio]

On 4/7/26 9:16 PM, Akhil P Oommen wrote:
> On 4/7/2026 4:31 PM, Konrad Dybcio wrote:
>> On 4/7/26 11:30 AM, Taniya Das wrote:
>>> From: Akhil P Oommen <akhilpo@xxxxxxxxxxxxxxxx>
>>>
>>> In A8x GPUs, the GX GDSC is moved to a separate block called GXCLKCTL
>>> which is under the GX power domain. Due to the way the support for this
>>> block is implemented in its driver, pm_runtime votes result in a vote on
>>> GX/GMxC/MxC rails from the APPS RSC. This is against the Adreno
>>> architecture which require GMU to be the sole voter of these collapsible
>>> rails on behalf of GPU, except during the GPU/GMU recovery.
>>>
>>> To align with this architectural requirement and to realize the power
>>> benefits of the IFPC feature, remove the GXPD votes during gmu resume
>>> and suspend. And during the recovery sequence, enable/disable the GXPD
>>> along with the 'synced_poweroff' genpd hint to force collapse this GDSC.
>>>
>>> Signed-off-by: Akhil P Oommen <akhilpo@xxxxxxxxxxxxxxxx>
>>> Signed-off-by: Taniya Das <taniya.das@xxxxxxxxxxxxxxxx>
>>> ---
>>
>> Can we simply make this change unconditional on the gen, so as not to
>> maintain 2 separate code paths that try to achieve mostly the same thing?
> 
> We can skip the gdsc vote on A8x because the 'gdsc disable' callback is
> dummy when the synced_poweroff hint is not set. Otherwise, gdsc may get
> disabled during system resume while GMU assumes the ownership. Taniya
> touched upon this point in the cover letter:
> 
> """
> when GX GDSC is managed through the generic GenPD runtime PM
> framework, it can be unintentionally disabled by the OS during system
> resume (resume_noirq/complete phases) or runtime PM suspend paths.
> """

Right, but if we made the GDSC.disable() a dummy on all platforms this
could be done.

On a second thought though, this won't work for gmu_wrapper, so we'd
need two paths either way.

Konrad