[PATCH v2] drm/nouveau/pmu: fix timeout on GP108

[Diego Viola]

Hi Ben,

On Wed, Feb 24, 2021 at 6:50 AM Ben Skeggs <skeggsb at gmail.com> wrote:
>
> On Wed, 17 Feb 2021 at 13:30, Alexandre Courbot <gnurou at gmail.com> wrote:
> >
> > On Wed, Feb 17, 2021 at 1:20 AM Diego Viola <diego.viola at gmail.com> wrote:
> > >
> > > This code times out on GP108, probably because the BIOS puts it into a
> > > bad state.
> > >
> > > Since we reset the PMU on driver load anyway, we are at no risk from
> > > missing a response from it since we are not waiting for one to begin
> > > with.
> >
> > This looks safe to me, provided indeed that the PMU's reset is not
> > called outside of initialization (which for GP108 is shouldn't be
> > IIRC?).
> ISTR that the PMU FW we use prior to GM200 might depend on that being there.
>
> I've posted a proposed alternate fix here[1], as we probably shouldn't
> have been touching PMU there anyway on those GPUs.
>
> Ben.
>
> [1] https://github.com/skeggsb/linux/commit/90224a17437b1f39dbecbb385567c1fce958f992
>
> >
> > >
> > > Signed-off-by: Diego Viola <diego.viola at gmail.com>
> > > ---
> > >  drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c | 6 +-----
> > >  1 file changed, 1 insertion(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c
> > > index a0fe607c9c07..5c802f2d00cb 100644
> > > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c
> > > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/pmu/base.c
> > > @@ -102,12 +102,8 @@ nvkm_pmu_reset(struct nvkm_pmu *pmu)
> > >         if (!pmu->func->enabled(pmu))
> > >                 return 0;
> > >
> > > -       /* Inhibit interrupts, and wait for idle. */
> > > +       /* Inhibit interrupts. */
> > >         nvkm_wr32(device, 0x10a014, 0x0000ffff);
> > > -       nvkm_msec(device, 2000,
> > > -               if (!nvkm_rd32(device, 0x10a04c))
> > > -                       break;
> > > -       );
> > >
> > >         /* Reset. */
> > >         if (pmu->func->reset)
> > > --
> > > 2.30.1
> > >
> > _______________________________________________
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> > dri-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel

I tested your patch and can confirm that the timeout is gone after
booting my system, but unfortunately it's back after doing a
suspend/resume.

Any ideas about that?

Thanks,
Diego