Re: [PATCH 3/9] arm64: dts: qcom: sc7280: Enable MDP turbo mode

[Dmitry Baryshkov]

On Thu, 22 Feb 2024 at 17:04, Bjorn Andersson <quic_bjorande@xxxxxxxxxxx> wrote:
>
> On Thu, Feb 22, 2024 at 11:46:26AM +0200, Dmitry Baryshkov wrote:
> > On Thu, 22 Feb 2024 at 11:28, Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> wrote:
> > >
> > >
> > >
> > > On 2/22/24 10:04, Dmitry Baryshkov wrote:
> > > > On Thu, 22 Feb 2024 at 10:56, Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> wrote:
> > > >>
> > > >>
> > > >>
> > > >> On 2/22/24 00:41, Dmitry Baryshkov wrote:
> > > >>> On Thu, 22 Feb 2024 at 01:19, Bjorn Andersson <quic_bjorande@xxxxxxxxxxx> wrote:
> > > >>>>
> > > >>>> The max frequency listed in the DPU opp-table is 506MHz, this is not
> > > >>>> sufficient to drive a 4k@60 display, resulting in constant underrun.
> > > >>>>
> > > >>>> Add the missing MDP_CLK turbo frequency of 608MHz to the opp-table to
> > > >>>> fix this.
> > > >>>
> > > >>> I think we might want to keep this disabled for ChromeOS devices. Doug?
> > > >>
> > > >> ChromeOS devices don't get a special SoC
> > > >
> > > > But they have the sc7280-chrome-common.dtsi, which might contain a
> > > > corresponding /delete-node/ .
> > >
> > > What does that change? The clock rates are bound to the
> > > SoC and the effective values are limited by link-frequencies
> > > or the panel driver.
> >
> > Preventing the DPU from overheating? Or spending too much power?
> >
>
> Perhaps I'm misunderstanding the implementation then, are we always
> running at the max opp? I thought the opp was selected based on the
> current need for performance?

Yes. My concern was whether the Chrome people purposely skipped this
top/turbo freq for any reason. In such a case, surprising them by
adding it to all platforms might be not the best idea. I hope Doug can
comment here.


-- 
With best wishes
Dmitry