[PATCH] drm/i915: implement hsw WaDisableVFUnitClockGating

[Daniel Vetter <daniel.vetter@ffwll.ch>]

Found while strolling for ilk workarounds since this one is listed
there, too. I think that's a mistake though, since the w/a isn't
listed for snb/ivb, and the relevant register doesn't seem to exist on
ilk.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/i915_reg.h |    1 +
 drivers/gpu/drm/i915/intel_pm.c |    7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index a4162dd..555a90f 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -4126,6 +4126,7 @@
 # define GEN6_CSUNIT_CLOCK_GATE_DISABLE			(1 << 7)
 
 #define GEN6_UCGCTL2				0x9404
+# define GEN7_VFUNIT_CLOCK_GATE_DISABLE		(1<<31)
 # define GEN7_VDSUNIT_CLOCK_GATE_DISABLE		(1 << 30)
 # define GEN7_TDLUNIT_CLOCK_GATE_DISABLE		(1 << 22)
 # define GEN6_RCZUNIT_CLOCK_GATE_DISABLE		(1 << 13)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 72f41aa..48bbcc1 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3507,8 +3507,11 @@ static void haswell_init_clock_gating(struct drm_device *dev)
 
 	/* According to the spec, bit 13 (RCZUNIT) must be set on IVB.
 	 * This implements the WaDisableRCZUnitClockGating workaround.
-	 */
-	I915_WRITE(GEN6_UCGCTL2, GEN6_RCZUNIT_CLOCK_GATE_DISABLE);
+	 * New w/a on hsw: bit 31 must be set, too. This implements for
+	 * WaDisableVFUnitClockGating */
+	I915_WRITE(GEN6_UCGCTL2,
+		   GEN6_RCZUNIT_CLOCK_GATE_DISABLE |
+		   GEN7_VFUNIT_CLOCK_GATE_DISABLE);
 
 	I915_WRITE(ILK_DSPCLK_GATE, IVB_VRHUNIT_CLK_GATE);
 
-- 
1.7.10.4