Re: [PATCH] drm/i915: enable WaDisableDopClkGating for gen9

[David Weinehall <david.weinehall@linux.intel.com>]

On Wed, Aug 02, 2017 at 12:24:33PM -0700, Rodrigo Vivi wrote:
> On Wed, Aug 2, 2017 at 10:34 AM, Praveen Paneri
> <praveen.paneri@intel.com> wrote:
> > This WA is required when decoupled frequencies for slice and unslice
> > are enabled. This disables DOP clock gating for gen9.
> >
> > v2: enable the WA for all gen9 platforms (not just for SKL GT4 where
> >     the hang issue is originally reported) to avoid rare hangs (David)
> >
> > Cc: David Weinehall <david.weinehall@linux.intel.com>
> > Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>
> > Signed-off-by: Praveen Paneri <praveen.paneri@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_pm.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index 3fc42aa..e369d77 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -88,6 +88,12 @@ static void gen9_init_clock_gating(struct drm_i915_private *dev_priv)
> >         /* WaFbcHighMemBwCorruptionAvoidance:skl,bxt,kbl,cfl */
> >         I915_WRITE(ILK_DPFC_CHICKEN, I915_READ(ILK_DPFC_CHICKEN) |
> >                    ILK_DPFC_DISABLE_DUMMY0);
> > +
> > +       if (IS_GEN9(dev_priv)) {
> 
> I believe we should go with IS_SKYLAKE(dev_priv)

Based on the info below that sounds sensible, yes. Good find.

> Bspec only list this Wa for:
> BDW: ALL
> CHV: UNTIL A7
> 
> WaDatabase only list this to:
> SKL: SIWA_FOREVER
> BDW: SIWA_FOREVER
> CHV: SIWA_CHV_UNTIL_A7
> SNB: SIWA_UNTIL_GT_MOBILE_D0

Do we currently apply the fix on SNB?

I must say that the list of platforms seem a bit arbitrary though; it
seems weird that an issue on Sandybridge would disappear on Ivybridge
and Haswell, then resurface again on Broadwell...

Then again, it happens far too often in software land, so it might very
well be that it happens in hardware land too.


Kind regards, David
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