[Intel-gfx] [PATCH 3/3] drm/i915: add L3 bank clock gating disable on IVB and VLV

[Jesse Barnes]

Prevents a possible hang.

References: https://bugs.freedesktop.org/show_bug.cgi?id=50245
Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
---
 drivers/gpu/drm/i915/i915_reg.h |    3 +++
 drivers/gpu/drm/i915/intel_pm.c |    4 ++++
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index f95b5cc..efac1e6 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3995,6 +3995,9 @@
 # define GEN6_RCPBUNIT_CLOCK_GATE_DISABLE		(1 << 12)
 # define GEN6_RCCUNIT_CLOCK_GATE_DISABLE		(1 << 11)
 
+#define GEN7_UCGCTL4				0x940c
+#define  GEN7_L3BANK2X_CLOCK_GATE_DISABLE	(1<<25)
+
 #define GEN6_RPNSWREQ				0xA008
 #define   GEN6_TURBO_DISABLE			(1<<31)
 #define   GEN6_FREQUENCY(x)			((x)<<25)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 26de27b..e8d977f 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3402,6 +3402,8 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
 		   GEN6_RCPBUNIT_CLOCK_GATE_DISABLE |
 		   GEN6_RCCUNIT_CLOCK_GATE_DISABLE);
 
+	I915_WRITE(GEN7_UCGCTL4, GEN7_L3BANK2X_CLOCK_GATE_DISABLE);
+
 	/* This is required by WaCatErrorRejectionIssue */
 	I915_WRITE(GEN7_SQ_CHICKEN_MBCUNIT_CONFIG,
 			I915_READ(GEN7_SQ_CHICKEN_MBCUNIT_CONFIG) |
@@ -3476,6 +3478,8 @@ static void valleyview_init_clock_gating(struct drm_device *dev)
 		   GEN6_RCPBUNIT_CLOCK_GATE_DISABLE |
 		   GEN6_RCCUNIT_CLOCK_GATE_DISABLE);
 
+	I915_WRITE(GEN7_UCGCTL4, GEN7_L3BANK2X_CLOCK_GATE_DISABLE);
+
 	for_each_pipe(pipe) {
 		I915_WRITE(DSPCNTR(pipe),
 			   I915_READ(DSPCNTR(pipe)) |
-- 
1.7.5.4