linux-kernel - Re: [PATCH v2 10/14] drm/msm/a6xx: Fix up A6XX protected registers

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Date:   Tue, 14 Feb 2023 17:28:50 -0800
From:   Rob Clark <robdclark@...il.com>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        linux-arm-msm@...r.kernel.org, andersson@...nel.org,
        agross@...nel.org, marijn.suijten@...ainline.org,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>,
        Chia-I Wu <olvaffe@...il.com>,
        Douglas Anderson <dianders@...omium.org>,
        Jonathan Marek <jonathan@...ek.ca>,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 10/14] drm/msm/a6xx: Fix up A6XX protected registers

On Tue, Feb 14, 2023 at 4:38 PM Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
>
>
>
> On 15.02.2023 01:10, Dmitry Baryshkov wrote:
> > On 14/02/2023 23:56, Rob Clark wrote:
> >> On Tue, Feb 14, 2023 at 9:32 AM Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
> >>>
> >>> One of the protected ranges was too small (compared to the data we
> >>> have downstream). Fix it.
> >>>
> >>> Fixes: 408434036958 ("drm/msm/a6xx: update/fix CP_PROTECT initialization")
> >>> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> >>> ---
> >>>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 2 +-
> >>>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> >>> index 503c750216e6..d6b38bfdb3b4 100644
> >>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> >>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> >>> @@ -690,7 +690,7 @@ static const u32 a6xx_protect[] = {
> >>>          A6XX_PROTECT_NORDWR(0x00800, 0x0082),
> >>>          A6XX_PROTECT_NORDWR(0x008a0, 0x0008),
> >>>          A6XX_PROTECT_NORDWR(0x008ab, 0x0024),
> >>> -       A6XX_PROTECT_RDONLY(0x008de, 0x00ae),
> >>> +       A6XX_PROTECT_RDONLY(0x008d0, 0x00bc),
> >>
> >> Nak, this is intentional, we need userspace to be able to configure
> >> the CP counters.  Otherwise this would break fdperf, perfetto, etc
> >>
> >> (although maybe we should comment where we diverge from downstream)
> >
> > Yes, please. Otherwise it is extremely hard to understand the reason for diversion between the vendor driver and our one.
> +1
>
> I am content with dropping this patch from this series, so long
> as you leave a clue for others to not scratch their heads on this!

Yeah, I admit it is kinda a trap as-is.  And makes things less obvious
what to do when porting from downstream.  When I get a few minutes
I'll double check that there weren't any other exceptions (I don't
think they were but it has been a while) and add some comments.

BR,
-R

> Konrad
> >
> >>
> >> BR,
> >> -R
> >>
> >>>          A6XX_PROTECT_NORDWR(0x00900, 0x004d),
> >>>          A6XX_PROTECT_NORDWR(0x0098d, 0x0272),
> >>>          A6XX_PROTECT_NORDWR(0x00e00, 0x0001),
> >>> --
> >>> 2.39.1
> >>>
> >