[Intel-gfx] [PATCH 12/18] drm/i915: disable GTT cache for huge-pages

[Matthew Auld]

As hinted by the comment and from actually testing 2M pages on a BDW
machine with the GTT cache enabled, we are definitely going to need keep
it disabled.

Signed-off-by: Matthew Auld <matthew.auld at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 570bd603f401..2bb49bada4ea 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -7544,10 +7544,10 @@ static void broadwell_init_clock_gating(struct drm_i915_private *dev_priv)
 
 	/*
 	 * WaGttCachingOffByDefault:bdw
-	 * GTT cache may not work with big pages, so if those
-	 * are ever enabled GTT cache may need to be disabled.
+	 * The GTT cache must be disabled if the system is planning to use
+	 * 2M/1G pages.
 	 */
-	I915_WRITE(HSW_GTT_CACHE_EN, GTT_CACHE_EN_ALL);
+	I915_WRITE(HSW_GTT_CACHE_EN, 0);
 
 	/* WaKVMNotificationOnConfigChange:bdw */
 	I915_WRITE(CHICKEN_PAR2_1, I915_READ(CHICKEN_PAR2_1)
@@ -7823,10 +7823,10 @@ static void cherryview_init_clock_gating(struct drm_i915_private *dev_priv)
 	gen8_set_l3sqc_credits(dev_priv, 38, 2);
 
 	/*
-	 * GTT cache may not work with big pages, so if those
-	 * are ever enabled GTT cache may need to be disabled.
+	 * The GTT cache must be disabled if the system is planning to use
+	 * 2M/1G pages.
 	 */
-	I915_WRITE(HSW_GTT_CACHE_EN, GTT_CACHE_EN_ALL);
+	I915_WRITE(HSW_GTT_CACHE_EN, 0);
 }
 
 static void g4x_init_clock_gating(struct drm_i915_private *dev_priv)
-- 
2.9.3