Received-SPF: pass (google.com: domain of linux-kernel+bounces-76983-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Precedence: bulk
MIME-Version: 1.0
References: <20240221-rb3gen2-dp-connector-v1-0-dc0964ef7d96@quicinc.com>
 <20240221-rb3gen2-dp-connector-v1-3-dc0964ef7d96@quicinc.com>
 <CAA8EJpo=9vhM+5YzaFxUoYRuEWQyrMS8wLNPSF3K=bN5JwWyDw@mail.gmail.com>
 <8313a7c3-3ace-4dee-ad27-8f51a06cd58c@linaro.org> <CAA8EJpqFj5nf8d_=Uoup7qg+nQrxqQU-DHbL3uSP138m9AcXLw@mail.gmail.com>
 <8fcb5816-2d59-4e27-ba68-8e0ed6e7d839@linaro.org> <CAA8EJporaUuddHHqpyYHiYSu=toHmrDxSHf9msZUJoym4Nz72g@mail.gmail.com>
 <20240222150423.GI2936378@hu-bjorande-lv.qualcomm.com>
In-Reply-To: <20240222150423.GI2936378@hu-bjorande-lv.qualcomm.com>
From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Thu, 22 Feb 2024 19:32:15 +0200
Message-ID: <CAA8EJpqd=1KV_dN8AURQDcFDDyO+YtbC59gM7ftt+HohGM93hg@mail.gmail.com>
Subject: Re: [PATCH 3/9] arm64: dts: qcom: sc7280: Enable MDP turbo mode
To: Bjorn Andersson <quic_bjorande@quicinc.com>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>, Douglas Anderson <dianders@chromium.org>, 
	Rob Clark <robdclark@gmail.com>, Abhinav Kumar <quic_abhinavk@quicinc.com>, 
	Sean Paul <sean@poorly.run>, Marijn Suijten <marijn.suijten@somainline.org>, 
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, cros-qcom-dts-watchers@chromium.org, 
	Bjorn Andersson <andersson@kernel.org>, Rob Herring <robh@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, 
	freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org, 
	devicetree@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"

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