linux-kernel - Re: [PATCH v2] drm/msm/adreno: Assign revn to A635

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Date:   Sun, 2 Jul 2023 07:31:27 -0700
From:   Rob Clark <robdclark@...il.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Stephen Boyd <swboyd@...omium.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Rob Clark <robdclark@...omium.org>
Subject: Re: [PATCH v2] drm/msm/adreno: Assign revn to A635

On Sat, Jul 1, 2023 at 5:24 PM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On Sat, 1 Jul 2023 at 18:50, Rob Clark <robdclark@...il.com> wrote:
> >
> > On Fri, Jun 30, 2023 at 4:12 PM Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
> > >
> > > Recently, a WARN_ON() was introduced to ensure that revn is filled before
> > > adreno_is_aXYZ is called. This however doesn't work very well when revn is
> > > 0 by design (such as for A635). Fill it in as a stopgap solution for
> > > -fixes.
> > >
> > > Fixes: cc943f43ece7 ("drm/msm/adreno: warn if chip revn is verified before being set")
> > > Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> > > ---
> > > Changes in v2:
> > > - add fixes
> > > - Link to v1: https://lore.kernel.org/r/20230628-topic-a635-v1-1-5056e09c08fb@linaro.org
> > > ---
> > >  drivers/gpu/drm/msm/adreno/adreno_device.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c
> > > index cb94cfd137a8..8ea7eae9fc52 100644
> > > --- a/drivers/gpu/drm/msm/adreno/adreno_device.c
> > > +++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
> > > @@ -345,6 +345,7 @@ static const struct adreno_info gpulist[] = {
> > >                 .address_space_size = SZ_16G,
> > >         }, {
> > >                 .rev = ADRENO_REV(6, 3, 5, ANY_ID),
> > > +               .revn = 635,
> > >                 .fw = {
> > >                         [ADRENO_FW_SQE] = "a660_sqe.fw",
> > >                         [ADRENO_FW_GMU] = "a660_gmu.bin",
> > >
> >
> > hmm, I realized a problem with this, it would change what
> > MSM_PARAM_GPU_ID and more importantly MSM_PARAM_CHIP_ID return..  The
> > former should be "harmless", although it isn't a good idea for uabi
> > changes to be a side effect of a fix.  The latter is more problematic.
>
> I'd say MSM_PARAM_GPU_ID is broken for 635 anyway (won't it return 0
> in this case)?
> So the new value should be correct.

no, it is very much intentional that GPU_ID returns 0 for newer GPUs,
userspace should be matching on CHIP_ID.  (Also, we should be moving
away from trying to infer generation/etc from CHIP_ID.. userspace is
farther ahead of the kernel on this.)

> But more importantly, why are we exporting speedbin in
> MSM_PARAM_CHIP_ID only if there is no revn? And why are we exporting
> the speedbin at all as a part of CHIP_ID?

Basically just being paranoid about not changing uabi.  It probably
would be ok to export the speedbin for all, but I'd have to double
check mesa version history.

BR,
-R

> >
> > I think I'm leaning more towards reverting commit cc943f43ece7
> > ("drm/msm/adreno: warn if chip revn is verified before being set") for
> > -fixes.  I'm still thinking about options for a longer term fix.
> >
> > BR,
> > -R
> >
> >
> > > ---
> > > base-commit: 5c875096d59010cee4e00da1f9c7bdb07a025dc2
> > > change-id: 20230628-topic-a635-1b3c2c987417
> > >
> > > Best regards,
> > > --
> > > Konrad Dybcio <konrad.dybcio@...aro.org>
> > >
>
>
>
> --
> With best wishes
> Dmitry