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

[Abhinav Kumar]

On 2/22/2024 1:46 AM, 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?

Running DPU clock in turbo is a requirement to support 4k@60 otherwise 
the pixel rate that high cannot be supported.

sc7280 chrome devices already limit to HBR2

https://lore.kernel.org/all/20230329233416.27152-1-quic_abhinavk@xxxxxxxxxxx/

So the DPU will not vote more than nominal.

And like others wrote, limiting SOC frequencies is not the way and we 
should filter out required frequencies using link-frequencies.

Hence fwiw, I am fine with this change.


Reviewed-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>