From be71eabebaf9f142612d34d42292b454e984dcb5 Mon Sep 17 00:00:00 2001
From: Rodrigo Vivi <rodrigo.vivi@intel.com>
Date: Mon, 4 Aug 2014 11:15:19 -0700
Subject: [PATCH] Revert "drm/i915: Enable semaphores on BDW"

This reverts commit 521e62e49a42661a4ee0102644517dbe2f100a23.

Although POST_SYNC brought a bit of stability to Semaphores on BDW
it didn't solved all issues and some hungs can still occour when
semaphores are enabled on BDW. Also some sloweness can be found on some
igt tests, althoguth it apparently doesn't affect real workloads.

Besides that, no real performance gain was found on our tests with different
and even multiple workloads.

Let's disable it again for now. At least until we are sure it is safe
to re-enable it.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/i915_drv.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 6c4b25ce8bb0..ec96f9a9724c 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -481,6 +481,10 @@ bool i915_semaphore_is_enabled(struct drm_device *dev)
 	if (i915.semaphores >= 0)
 		return i915.semaphores;
 
+	/* Until we get further testing... */
+	if (IS_GEN8(dev))
+		return false;
+
 #ifdef CONFIG_INTEL_IOMMU
 	/* Enable semaphores on SNB when IO remapping is off */
 	if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped)
-- 
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