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

[Dmitry Baryshkov]

On 02/07/2023 17:31, Rob Clark wrote:
> On Sat, Jul 1, 2023 at 5:24 PM Dmitry Baryshkov
> <dmitry.baryshkov@xxxxxxxxxx> wrote:
> > On Sat, 1 Jul 2023 at 18:50, Rob Clark <robdclark@xxxxxxxxx> wrote:
> > > On Fri, Jun 30, 2023 at 4:12 PM Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> 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@xxxxxxxxxx>
> > > > ---
> > > > Changes in v2:
> > > > - add fixes
> > > > - Link to v1: https://lore.kernel.org/r/20230628-topic-a635-v1-1-5056e09c08fb@xxxxxxxxxx
> > > > ---
> > > >   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.)

Thanks for the explanation. So in theory we can change this to always 
return 0? Or must we keep it to keep UABI / compatibility?

I'm trying to understand if we can drop revn at all.


> > 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.

Thanks!

> 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@xxxxxxxxxx>
> >
> >
> >
> > --
> > With best wishes
> > Dmitry

--
With best wishes
Dmitry