[PATCH] drm/amdgpu: keep mmhub clock gating being enabled during s2idle suspend

[Liang, Prike]

[Public]

> -----Original Message-----
> From: Lazar, Lijo <Lijo.Lazar at amd.com>
> Sent: Tuesday, April 26, 2022 7:19 PM
> To: Liang, Prike <Prike.Liang at amd.com>; amd-gfx at lists.freedesktop.org
> Cc: Deucher, Alexander <Alexander.Deucher at amd.com>; Huang, Ray
> <Ray.Huang at amd.com>
> Subject: Re: [PATCH] drm/amdgpu: keep mmhub clock gating being enabled
> during s2idle suspend
>
>
>
> On 4/25/2022 12:22 PM, Prike Liang wrote:
> > Without MMHUB clock gating being enabled then MMHUB will not
> > disconnect from DF and will result in DF C-state entry can't be
> > accessed during S2idle suspend, and eventually s0ix entry will be blocked.
> >
> > Signed-off-by: Prike Liang <Prike.Liang at amd.com>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c | 10 ++++++++++
> >   1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> > b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> > index a455e59f41f4..20946bc7fc93 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> > @@ -1151,6 +1151,16 @@ static int gmc_v10_0_set_clockgating_state(void
> *handle,
> >     int r;
> >     struct amdgpu_device *adev = (struct amdgpu_device *)handle;
> >
> > +   /*
> > +    * The issue mmhub can't disconnect from DF with MMHUB clock
> gating being disabled
> > +    * is a new problem observed at DF 3.0.3, however with the same
> suspend sequence not
> > +    * seen any issue on the DF 3.0.2 series platform.
> > +    */
> > +   if (adev->in_s0ix && adev->ip_versions[DF_HWIP][0] > IP_VERSION(3,
> 0, 2)) {
> > +           dev_dbg(adev->dev, "keep mmhub clock gating being
> enabled for s0ix\n");
> > +           return 0;
> > +   }
> > +
>
> This only ignores clock gating requests as long as s0ix flag is set. As far as I
> see, s0ix flag is set to true even during resume and set to false only after
> resume is completed. Is that intention and is this tested to be working fine? I
> suggest to keep this specifically for suspend calls.
>
> Thanks,
> Lijo
>
It reasonable for also not reenable the clock gating on the s2ilde resume since clock gating
not disabled on the s2idle suspend. Have merged the fix for not blocking s0ix support for some
upcoming asic and meanwhile still need dig into whether the DF C-state, MMHUB DS or BIOS mmhub power gate request different on GC 10.3.7 introduce this issue and then make a generic solution for such this issue.

> >     r = adev->mmhub.funcs->set_clockgating(adev, state);
> >     if (r)
> >             return r;
> >