linux-kernel - Re: [PATCH v2] arm64: dts: qcom: disable GPU on x1e80100 by default

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Message-ID: <CAF6AEGvmuzMcYz+oqu+GKhhxYqc8SqKcThY5CvR6tnES-Lu71A@mail.gmail.com>
Date: Tue, 16 Jul 2024 07:49:07 -0700
From: Rob Clark <robdclark@...il.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Akhil P Oommen <quic_akhilpo@...cinc.com>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konrad.dybcio@...aro.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Rob Clark <robdclark@...omium.org>
Subject: Re: [PATCH v2] arm64: dts: qcom: disable GPU on x1e80100 by default

On Tue, Jul 16, 2024 at 4:03 AM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On Mon, 15 Jul 2024 at 22:01, Akhil P Oommen <quic_akhilpo@...cinc.com> wrote:
> >
> > On Mon, Jul 15, 2024 at 09:18:49PM +0300, Dmitry Baryshkov wrote:
> > > The GPU on X1E80100 requires ZAP 'shader' file to be useful. Since the
> > > file is signed by the OEM keys and might be not available by default,
> > > disable the GPU node and drop the firmware name from the x1e80100.dtsi
> > > file. Devices not being fused to use OEM keys can specify generic
> > > location at `qcom/x1e80100/gen70500_zap.mbn` while enabling the GPU.
> > >
> > > The CRD was lucky enough to work with the default settings, so reenable
> > > the GPU on that platform and provide correct firmware-name (including
> > > the SoC subdir).
> > >
> > > Fixes: 721e38301b79 ("arm64: dts: qcom: x1e80100: Add gpu support")
> > > Cc: Akhil P Oommen <quic_akhilpo@...cinc.com>
> > > Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > > ---
> > > Changes in v2:
> > > - Keep GPU enabled for X1E80100-CRD (Johan)
> > > - Link to v1: https://lore.kernel.org/r/20240715-x1e8-zap-name-v1-1-b66df09d0b65@linaro.org
> > > ---
> > >  arch/arm64/boot/dts/qcom/x1e80100-crd.dts | 8 ++++++++
> > >  arch/arm64/boot/dts/qcom/x1e80100.dtsi    | 3 ++-
> > >  2 files changed, 10 insertions(+), 1 deletion(-)
> > >
>
> [..]
>
> > > diff --git a/arch/arm64/boot/dts/qcom/x1e80100.dtsi b/arch/arm64/boot/dts/qcom/x1e80100.dtsi
> > > index 7bca5fcd7d52..8df90d01eba8 100644
> > > --- a/arch/arm64/boot/dts/qcom/x1e80100.dtsi
> > > +++ b/arch/arm64/boot/dts/qcom/x1e80100.dtsi
> > > @@ -3155,9 +3155,10 @@ gpu: gpu@...0000 {
> > >                       interconnects = <&gem_noc MASTER_GFX3D 0 &mc_virt SLAVE_EBI1 0>;
> > >                       interconnect-names = "gfx-mem";
> > >
> > > +                     status = "disabled";
> > > +
> > >                       zap-shader {
> > >                               memory-region = <&gpu_microcode_mem>;
> > > -                             firmware-name = "qcom/gen70500_zap.mbn";
> >
> > In general, why not keep a default zap firmware listed here? Anyway we
> > are disabling gpu node here in case of platforms which doesn't upstream
> > secure firmwares.
>
> Excuse me, I missed the question before sending v3, however the answer
> is still going to be the same:
>
> First of all, we don't do it for other platforms
> Second, we don't do it for other firmware. Each DT declares its own
> set of files.
> Last, but not least, it's better to get an error message regarding
> firmware-name not being present rather than a possibly cryptic message
> regarding firmware failing authentication.

tbh, I think it might be better to just remove the default fw name
from a6xx_catalog.c device table.  That would better reflect the
situation, ie. some fw is needed and not available (if the
firmware-name prop isn't provided).  Trying to fall back to loading
the wrong fw is a mis-design.

BR,
-R

> >
> > -Akhil
> >
> > >                       };
> > >
> > >                       gpu_opp_table: opp-table {
> > >
> > > ---
> > > base-commit: 3fe121b622825ff8cc995a1e6b026181c48188db
> > > change-id: 20240715-x1e8-zap-name-7b3c79234401
> > >
> > > Best regards,
> > > --
> > > Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > >
>
>
>
> --
> With best wishes
> Dmitry
>