drm/i915: tune Sandy Bridge DRPS constants

These make us increase our frequency much more readily, and decrease
them only after significant idle time, resulting in a 20% performance
increase for nexuiz.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index cb9d547..a90d65d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6630,18 +6630,18 @@
 	I915_WRITE(GEN6_RP_INTERRUPT_LIMITS,
 		   18 << 24 |
 		   6 << 16);
-	I915_WRITE(GEN6_RP_UP_THRESHOLD, 90000);
-	I915_WRITE(GEN6_RP_DOWN_THRESHOLD, 100000);
+	I915_WRITE(GEN6_RP_UP_THRESHOLD, 10000);
+	I915_WRITE(GEN6_RP_DOWN_THRESHOLD, 1000000);
 	I915_WRITE(GEN6_RP_UP_EI, 100000);
-	I915_WRITE(GEN6_RP_DOWN_EI, 300000);
+	I915_WRITE(GEN6_RP_DOWN_EI, 5000000);
 	I915_WRITE(GEN6_RP_IDLE_HYSTERSIS, 10);
 	I915_WRITE(GEN6_RP_CONTROL,
 		   GEN6_RP_MEDIA_TURBO |
 		   GEN6_RP_USE_NORMAL_FREQ |
 		   GEN6_RP_MEDIA_IS_GFX |
 		   GEN6_RP_ENABLE |
-		   GEN6_RP_UP_BUSY_MAX |
-		   GEN6_RP_DOWN_BUSY_MIN);
+		   GEN6_RP_UP_BUSY_AVG |
+		   GEN6_RP_DOWN_IDLE_CONT);
 
 	if (wait_for((I915_READ(GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY) == 0,
 		     500))