From 666a130a1a9046994d8a3c5c3ff62316ed980ba6 Mon Sep 17 00:00:00 2001
From: Eugeni Dodonov <eugeni.dodonov@intel.com>
Date: Fri, 23 Mar 2012 11:57:19 -0300
Subject: [PATCH 2/2] drm/i915: enable plain RC6 on Sandy Bridge by default

This is yet another chapter in the ongoing saga of bringing RC6 to Sandy
Bridge machines by default.

Now that we have discovered that RC6 issues are triggered by RC6+ state,
let's try to disable it by default. Plain RC6 is the one responsible for
most energy savings, and so far it haven't given any problems - at least,
none we are aware of.

So with this, when i915_enable_rc6=-1 (e.g., the default value), we'll
attempt to enable plain RC6 only on SNB. For Ivy Bridge, the behavior
stays the same as always - we enable both RC6 and deep RC6.

Note that while this exact patch does not has explicit tested-by's, the
equivalent settings were fixed in 3.3 kernel by a smaller patch. And it
has also received considerable testing through Canonical RC6 task-force
testing at https://wiki.ubuntu.com/Kernel/PowerManagementRC6. Up to date,
it looks like all the known issues are gone.

v2: improve description and reference a couple of open bugs related to
RC6 which seem to be fixed with this change.

References: https://bugs.freedesktop.org/show_bug.cgi?id=41682
References: https://bugs.freedesktop.org/show_bug.cgi?id=38567
References: https://bugs.freedesktop.org/show_bug.cgi?id=44867
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/intel_display.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 1430f09..0fad1b3 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8150,11 +8150,11 @@ static int intel_enable_rc6(struct drm_device *dev)
 	 * Disable rc6 on Sandybridge
 	 */
 	if (INTEL_INFO(dev)->gen == 6) {
-		DRM_DEBUG_DRIVER("Sandybridge: RC6 disabled\n");
-		return 0;
+		DRM_DEBUG_DRIVER("Sandybridge: deep RC6 disabled\n");
+		return INTEL_RC6_ENABLE;
 	}
-	DRM_DEBUG_DRIVER("RC6 enabled\n");
-	return 1;
+	DRM_DEBUG_DRIVER("RC6 and deep RC6 enabled\n");
+	return (INTEL_RC6_ENABLE | INTEL_RC6p_ENABLE);
 }
 
 void gen6_enable_rps(struct drm_i915_private *dev_priv)
-- 
1.7.9.3