[Intel-gfx] [PATCH] drm/i915/gt: Disable HiZ Raw Stall Optimization on broken gen7

[Rodrigo Vivi]

On Thu, May 13, 2021 at 10:18:49AM +1000, Dave Airlie wrote:
> Reviewed-by: Dave Airlie <airlied at redhat.com>
> 
> Can we get this fix in, having a regression spanning 3 kernels isn't a
> good look, we can work out why it matters later in life if anyone
> cares.

Agreed and pushed do drm-intel-next.

This triggered me to do an archeology work here and I found a possible
alternative for ILK:

+#define   HIZ_UNIT_CLOCK_GATE_DISABLE  REG_BIT(5)
 
 #define FDI_PLL_FREQ_CTL        _MMIO(0x46030)
 #define  FDI_PLL_FREQ_CHANGE_REQUEST    (1 << 24)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 06d5b7cc8b62..6316b70978f7 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6892,8 +6892,11 @@ static void ilk_init_clock_gating(struct drm_i915_private *dev_priv)
        intel_uncore_write(&dev_priv->uncore, PCH_3DCGDIS0,
                   MARIUNIT_CLOCK_GATE_DISABLE |
                   SVSMUNIT_CLOCK_GATE_DISABLE);
+
+       /* WaDisableHizUnitClockGating:ilk */
        intel_uncore_write(&dev_priv->uncore, PCH_3DCGDIS1,
-                  VFMUNIT_CLOCK_GATE_DISABLE);
+                  VFMUNIT_CLOCK_GATE_DISABLE |
+                  HIZ_UNIT_CLOCK_GATE_DISABLE);

however I couldn't find anything for Baytrail, so let's move with this
one for now.

> 
> Dave.
> 
> On Tue, 27 Apr 2021 at 00:31, Simon Rettberg
> <simon.rettberg at rz.uni-freiburg.de> wrote:
> >
> > When resetting CACHE_MODE registers, don't enable HiZ Raw Stall
> > Optimization on Ivybridge GT1 and Baytrail, as it causes severe glitches
> > when rendering any kind of 3D accelerated content.
> > This optimization is disabled on these platforms by default according to
> > official documentation from 01.org.
> >
> > Fixes: ef99a60ffd9b ("drm/i915/gt: Clear CACHE_MODE prior to clearing residuals")
> > Fixes: 520d05a77b28 ("drm/i915/gt: Clear CACHE_MODE prior to clearing residuals")
> > BugLink: https://gitlab.freedesktop.org/drm/intel/-/issues/3081
> > BugLink: https://gitlab.freedesktop.org/drm/intel/-/issues/3404
> > BugLink: https://gitlab.freedesktop.org/drm/intel/-/issues/3071
> > Reviewed-By: Manuel Bentele <development at manuel-bentele.de>
> > Signed-off-by: Simon Rettberg <simon.rettberg at rz.uni-freiburg.de>
> > ---
> >  drivers/gpu/drm/i915/gt/gen7_renderclear.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/gen7_renderclear.c b/drivers/gpu/drm/i915/gt/gen7_renderclear.c
> > index de575fdb0..21f08e538 100644
> > --- a/drivers/gpu/drm/i915/gt/gen7_renderclear.c
> > +++ b/drivers/gpu/drm/i915/gt/gen7_renderclear.c
> > @@ -397,7 +397,10 @@ static void emit_batch(struct i915_vma * const vma,
> >         gen7_emit_pipeline_invalidate(&cmds);
> >         batch_add(&cmds, MI_LOAD_REGISTER_IMM(2));
> >         batch_add(&cmds, i915_mmio_reg_offset(CACHE_MODE_0_GEN7));
> > -       batch_add(&cmds, 0xffff0000);
> > +       batch_add(&cmds, 0xffff0000 |
> > +                       ((IS_IVB_GT1(i915) || IS_VALLEYVIEW(i915)) ?
> > +                        HIZ_RAW_STALL_OPT_DISABLE :
> > +                        0));
> >         batch_add(&cmds, i915_mmio_reg_offset(CACHE_MODE_1));
> >         batch_add(&cmds, 0xffff0000 | PIXEL_SUBSPAN_COLLECT_OPT_DISABLE);
> >         gen7_emit_pipeline_invalidate(&cmds);
> > --
> > 2.25.1
> >
> > _______________________________________________
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> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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