[Intel-gfx] [PATCH] drm/i915/bdw: Use timeout mode for RC6 on bdw

[Tom O'Rourke]

Higher RC6 residency is observed using timeout mode
instead of EI mode.  This applies to Broadwell only.
The difference is particularly noticeable with video
playback.

Issue: VIZ-3778
Change-Id: I62bb12e21caf19651034826b45cde7f73a80938d
Signed-off-by: Tom O'Rourke <Tom.O'Rourke at intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c |   16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 33b2592..0d63abf 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3335,15 +3335,23 @@ static void gen8_enable_rps(struct drm_device *dev)
 	for_each_ring(ring, dev_priv, unused)
 		I915_WRITE(RING_MAX_IDLE(ring->mmio_base), 10);
 	I915_WRITE(GEN6_RC_SLEEP, 0);
-	I915_WRITE(GEN6_RC6_THRESHOLD, 50000); /* 50/125ms per EI */
+	if (IS_BROADWELL(dev))
+		I915_WRITE(GEN6_RC6_THRESHOLD, 625); /* 800us/1.28 for TO */
+	else
+		I915_WRITE(GEN6_RC6_THRESHOLD, 50000); /* 50/125ms per EI */
 
 	/* 3: Enable RC6 */
 	if (intel_enable_rc6(dev) & INTEL_RC6_ENABLE)
 		rc6_mask = GEN6_RC_CTL_RC6_ENABLE;
 	intel_print_rc6_info(dev, rc6_mask);
-	I915_WRITE(GEN6_RC_CONTROL, GEN6_RC_CTL_HW_ENABLE |
-				    GEN6_RC_CTL_EI_MODE(1) |
-				    rc6_mask);
+	if (IS_BROADWELL(dev))
+		I915_WRITE(GEN6_RC_CONTROL, GEN6_RC_CTL_HW_ENABLE |
+				GEN7_RC_CTL_TO_MODE |
+				rc6_mask);
+	else
+		I915_WRITE(GEN6_RC_CONTROL, GEN6_RC_CTL_HW_ENABLE |
+				GEN6_RC_CTL_EI_MODE(1) |
+				rc6_mask);
 
 	/* 4 Program defaults and thresholds for RPS*/
 	I915_WRITE(GEN6_RPNSWREQ,
-- 
1.7.9.5