[Intel-gfx] [PATCH] drm/i915: Wait for pending flips to complete before tearing down the encoders

[Chris Wilson]

If we start disabling the encoders, there is a potential for a pending
flip to never occur - and so we will end up waiting indefinitely.

References: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1097315
Cc: Timo Aaltonen <tjaalton at ubuntu.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_display.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index da1ad9c..dbd8895 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3486,14 +3486,14 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
 	int plane = intel_crtc->plane;
 	u32 reg, temp;
 
-
 	if (!intel_crtc->active)
 		return;
 
+	intel_crtc_wait_for_pending_flips(crtc);
+
 	for_each_encoder_on_crtc(dev, crtc, encoder)
 		encoder->disable(encoder);
 
-	intel_crtc_wait_for_pending_flips(crtc);
 	drm_vblank_off(dev, pipe);
 	intel_crtc_update_cursor(crtc, false);
 
@@ -3570,12 +3570,13 @@ static void haswell_crtc_disable(struct drm_crtc *crtc)
 	if (!intel_crtc->active)
 		return;
 
+	intel_crtc_wait_for_pending_flips(crtc);
+
 	is_pch_port = haswell_crtc_driving_pch(crtc);
 
 	for_each_encoder_on_crtc(dev, crtc, encoder)
 		encoder->disable(encoder);
 
-	intel_crtc_wait_for_pending_flips(crtc);
 	drm_vblank_off(dev, pipe);
 	intel_crtc_update_cursor(crtc, false);
 
@@ -3687,15 +3688,15 @@ static void i9xx_crtc_disable(struct drm_crtc *crtc)
 	int pipe = intel_crtc->pipe;
 	int plane = intel_crtc->plane;
 
-
 	if (!intel_crtc->active)
 		return;
 
+	intel_crtc_wait_for_pending_flips(crtc);
+
 	for_each_encoder_on_crtc(dev, crtc, encoder)
 		encoder->disable(encoder);
 
 	/* Give the overlay scaler a chance to disable if it's on this pipe */
-	intel_crtc_wait_for_pending_flips(crtc);
 	drm_vblank_off(dev, pipe);
 	intel_crtc_dpms_overlay(intel_crtc, false);
 	intel_crtc_update_cursor(crtc, false);
-- 
1.7.10.4