[RFC PATCH 0/3] drm/msm/a5xx: scale MX following the frequency changes

[Konrad Dybcio]

On 30.03.2023 13:15, Dmitry Baryshkov wrote:
> On 30/03/2023 14:06, Konrad Dybcio wrote:
>>
>>
>> On 30.03.2023 00:24, Dmitry Baryshkov wrote:
>>> Konrad brought up the topic of scaling the MX domain according to the
>>> OPP changes. Here is my RFC for this functionality. I post it as an RFC
>>> for two reasons:
>>>
>>> 1) I'm not sure that we should scale MX if we are not scaling main
>>> voltage following the CPR3
>> It should be ok, however..
>>>
>> [...]
>>
>>> Dmitry Baryshkov (3):
>>>    dt-bindings: display/msm/gpu: allow specifying MX domain A5xx
>>>    drm/msm/a5xx: scale MX domain following the frequncy changes
>> This is a stopgap solution, CPR is a child of MX.
> 
> Not so sure here. Vendor kernel scales voltages and MX levels separately. Moreover, please correct me if I'm wrong here, the kernel doesn't scale VDD_GFX directly. It programs GPMU's voltage table and then GPMU handles voltage scaling according to performance levels being set. MX is handled in parallel to switching GPMU's level.
> 
> I have implemented this voltage scaling locally, just need to run more tests before posting (and unfortunately it depends either on CPR3+GFX or on programming the voltages manually).
Oh no.. I forgot about the ugly goblin that we call GPMU.. I'll have
to dig into it further. Thanks for reminding me..

Konrad
> 
>>
>> Konrad
>>>    arm64: dts: qcom: specify power domains for the GPU
>>>
>>>   .../devicetree/bindings/display/msm/gpu.yaml  |  9 +++-
>>>   arch/arm64/boot/dts/qcom/msm8996.dtsi         | 14 ++++-
>>>   drivers/gpu/drm/msm/adreno/a5xx_gpu.c         | 52 +++++++++++++++++++
>>>   drivers/gpu/drm/msm/adreno/a5xx_gpu.h         |  3 ++
>>>   4 files changed, 76 insertions(+), 2 deletions(-)
>>>
>