[PATCH] Revert "drm/i915: enable rc6 on ilk again"

[Chris Wilson <chris@chris-wilson.co.uk>]

Even with the cumulative set of ilk w/a, rc6 is demonstrably still
failing and causing GPU hangs as found by Peter Wu. So we need to disable
it again until it is stable.

This reverts

commit 456470eb583f063ee84c6818251e638598be0fb8
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Aug 8 23:35:40 2012 +0200

    drm/i915: enable rc6 on ilk again

and the follow-on

commit cd7988eea561a70a4f98e431c1395f913672d626
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Sun Aug 26 20:33:18 2012 +0200

    drm/i915: disable rc6 on ilk when vt-d is enabled

Reported-by: Peter Wu <lekensteyn@gmail.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=55984
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_pm.c |   12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 4018ef4..2bda628 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2381,15 +2381,9 @@ int intel_enable_rc6(const struct drm_device *dev)
 	if (i915_enable_rc6 >= 0)
 		return i915_enable_rc6;
 
-	if (INTEL_INFO(dev)->gen == 5) {
-#ifdef CONFIG_INTEL_IOMMU
-		/* Disable rc6 on ilk if VT-d is on. */
-		if (intel_iommu_gfx_mapped)
-			return false;
-#endif
-		DRM_DEBUG_DRIVER("Ironlake: only RC6 available\n");
-		return INTEL_RC6_ENABLE;
-	}
+	/* Disable RC6 on Ironlake */
+	if (INTEL_INFO(dev)->gen == 5)
+		return 0;
 
 	if (IS_HASWELL(dev)) {
 		DRM_DEBUG_DRIVER("Haswell: only RC6 available\n");
-- 
1.7.10.4