linux-kernel - Re: [PATCH 3/4] drm/msm/adreno: Expose speedbin to userspace

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Date:   Thu, 13 Jan 2022 10:13:00 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Rob Clark <robdclark@...il.com>
Cc:     Akhil P Oommen <quic_akhilpo@...cinc.com>,
        freedreno <freedreno@...ts.freedesktop.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS 
        <devicetree@...r.kernel.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Christian König <christian.koenig@....com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Jonathan Marek <jonathan@...ek.ca>,
        Jordan Crouse <jordan@...micpenguin.net>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Sean Paul <sean@...rly.run>,
        Stephen Boyd <swboyd@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/4] drm/msm/adreno: Expose speedbin to userspace

On Thu, 13 Jan 2022 at 00:19, Rob Clark <robdclark@...il.com> wrote:
>
> On Tue, Jan 11, 2022 at 1:31 PM Akhil P Oommen <quic_akhilpo@...cinc.com> wrote:
> >
> > Expose speedbin through MSM_PARAM_CHIP_ID parameter to help userspace
> > identify the sku.
> >
> > Signed-off-by: Akhil P Oommen <quic_akhilpo@...cinc.com>
> > ---
> >
> >  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 9 +++++----
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > index f33cfa4..e970e6a 100644
> > --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > @@ -242,10 +242,11 @@ int adreno_get_param(struct msm_gpu *gpu, uint32_t param, uint64_t *value)
> >                 *value = !adreno_is_a650_family(adreno_gpu) ? 0x100000 : 0;
> >                 return 0;
> >         case MSM_PARAM_CHIP_ID:
> > -               *value = adreno_gpu->rev.patchid |
> > -                               (adreno_gpu->rev.minor << 8) |
> > -                               (adreno_gpu->rev.major << 16) |
> > -                               (adreno_gpu->rev.core << 24);
> > +               *value = (uint64_t) adreno_gpu->rev.patchid |
> > +                               (uint64_t) (adreno_gpu->rev.minor << 8) |
> > +                               (uint64_t) (adreno_gpu->rev.major << 16) |
> > +                               (uint64_t) (adreno_gpu->rev.core << 24) |
> > +                               (((uint64_t) adreno_gpu->rev.sku) << 32);
>
> How about this instead, so we are only changing the behavior for
> new/unreleased devices:
>
> *value = adreno_gpu->rev.patchid |
> (adreno_gpu->rev.minor << 8) |
> (adreno_gpu->rev.major << 16) |
> (adreno_gpu->rev.core << 24);
> if (!adreno_gpu->info->revn)
> *value |= (((uint64_t) adreno_gpu->rev.sku) << 32);
>
> (sorry about the butchered indentation.. somehow gmail has become
> antagonistic about pasting code)

I assume that you would like to keep userspace compat for older chips.
thus the if.
Maybe we should introduce MSM_PARAM_CHIP_ID_SKU instead (and gradually
make userspace switch to it)?

>
> BR,
> -R
>
> >                 return 0;
> >         case MSM_PARAM_MAX_FREQ:
> >                 *value = adreno_gpu->base.fast_rate;
> > --
> > 2.7.4
> >



-- 
With best wishes
Dmitry