[PATCH 2/2] drm/i915: Revert extra intel_wait_for_vblank to prevent stalls.

[Sitsofe Wheeler]

With the extra intel_wait_for_vblank added in commit
9d0498a2bf7455159b317f19531a3e5db2ecc9c4 periodic stalls were being
triggered (which were detected by i915_hangcheck_elapsed). Partially
revert this change for now.

Signed-off-by: Sitsofe Wheeler <sitsofe at yahoo.com>
---
 drivers/gpu/drm/i915/intel_display.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 116d938..534f1fa 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2379,8 +2379,10 @@ static void i9xx_crtc_dpms(struct drm_crtc *crtc, int mode)
 			I915_READ(dspbase_reg);
 		}
 
-		/* Wait for vblank for the disable to take effect */
-		intel_wait_for_vblank_off(dev, pipe);
+		if (!IS_I9XX(dev)) {
+			/* Wait for vblank for the disable to take effect */
+			intel_wait_for_vblank_off(dev, pipe);
+		}
 
 		/* Don't disable pipe A or pipe A PLLs if needed */
 		if (pipeconf_reg == PIPEACONF &&
-- 
1.7.1