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

[Dmitry Baryshkov]

On Thu, 30 Mar 2023 at 14:16, Konrad Dybcio <konrad.dybcio at linaro.org> wrote:
>
>
>
> 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..

Let me send the fixed voltage table programming (probably on Friday).

>
> 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(-)
> >>>
> >



-- 
With best wishes
Dmitry