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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Thu, 22 Feb 2024 19:32:15 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Bjorn Andersson <quic_bjorande@...cinc.com>
Cc: Konrad Dybcio <konrad.dybcio@...aro.org>, Douglas Anderson <dianders@...omium.org>, 
	Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>, 
	Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, cros-qcom-dts-watchers@...omium.org, 
	Bjorn Andersson <andersson@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	devicetree@...r.kernel.org
Subject: Re: [PATCH 3/9] arm64: dts: qcom: sc7280: Enable MDP turbo mode

On Thu, 22 Feb 2024 at 17:04, Bjorn Andersson <quic_bjorande@...cinc.com> 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@...aro.org> wrote:
> > >
> > >
> > >
> > > On 2/22/24 10:04, Dmitry Baryshkov wrote:
> > > > On Thu, 22 Feb 2024 at 10:56, Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
> > > >>
> > > >>
> > > >>
> > > >> On 2/22/24 00:41, Dmitry Baryshkov wrote:
> > > >>> On Thu, 22 Feb 2024 at 01:19, Bjorn Andersson <quic_bjorande@...cinc.com> 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