linux-kernel - Re: [PATCH] drm/msm/adreno: Make adreno quirks not overwrite each other

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Date:   Sun, 1 Jan 2023 14:18:11 -0800
From:   Rob Clark <robdclark@...il.com>
To:     Marijn Suijten <marijn.suijten@...ainline.org>
Cc:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-arm-msm@...r.kernel.org, andersson@...nel.org,
        agross@...nel.org, krzysztof.kozlowski@...aro.org,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>,
        Emma Anholt <emma@...olt.net>,
        Jordan Crouse <jordan@...micpenguin.net>,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/msm/adreno: Make adreno quirks not overwrite each other

On Thu, Dec 29, 2022 at 2:47 AM Marijn Suijten
<marijn.suijten@...ainline.org> wrote:
>
> On 2022-12-29 11:18:45, Konrad Dybcio wrote:
> > So far the adreno quirks have all been assigned with an OR operator,
> > which is problematic, because they were assigned consecutive integer
> > values, which makes checking them with an AND operator kind of no bueno..
> >
> > Switch to using BIT(n) so that only the quirks that the programmer chose
> > are taken into account when evaluating info->quirks & ADRENO_QUIRK_...
> >
> > Fixes: b5f103ab98c7 ("drm/msm: gpu: Add A5XX target support")
> > Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
>
> Nice catch!
>
> Reviewed-by: Marijn Suijten <marijn.suijten@...ainline.org>
>
> Not sure if it's the right Fixes commit though, as it would have worked
> when ADRENO_QUIRK_LMLOADKILL_DISABLE was added with constant 4 instead
> of 3 in 370063ee427a ("drm/msm/adreno: Add A540 support"), but then
> using bitflags in an enum value type is invalid anyway, AFAIK.

It isn't a thing that c++ like so much, but for c code, gdb will
decode enum bitfields in a sensible way (IIRC).  Also, maybe it
doesn't matter at this point, but it would conflict for stable
backports prior to adding LMLOADKILL_DISABLE.

with the fixes msg corrected,

Reviewed-by: Rob Clark <robdclark@...il.com>

> - Marijn
>
> > ---
> >  drivers/gpu/drm/msm/adreno/adreno_gpu.h | 10 ++++------
> >  1 file changed, 4 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> > index c85857c0a228..5eb254c9832a 100644
> > --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> > +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> > @@ -29,11 +29,9 @@ enum {
> >       ADRENO_FW_MAX,
> >  };
> >
> > -enum adreno_quirks {
> > -     ADRENO_QUIRK_TWO_PASS_USE_WFI = 1,
> > -     ADRENO_QUIRK_FAULT_DETECT_MASK = 2,
> > -     ADRENO_QUIRK_LMLOADKILL_DISABLE = 3,
> > -};
> > +#define ADRENO_QUIRK_TWO_PASS_USE_WFI                BIT(0)
> > +#define ADRENO_QUIRK_FAULT_DETECT_MASK               BIT(1)
> > +#define ADRENO_QUIRK_LMLOADKILL_DISABLE              BIT(2)
> >
> >  struct adreno_rev {
> >       uint8_t  core;
> > @@ -65,7 +63,7 @@ struct adreno_info {
> >       const char *name;
> >       const char *fw[ADRENO_FW_MAX];
> >       uint32_t gmem;
> > -     enum adreno_quirks quirks;
> > +     u64 quirks;
> >       struct msm_gpu *(*init)(struct drm_device *dev);
> >       const char *zapfw;
> >       u32 inactive_period;
> > --
> > 2.39.0
> >