[Intel-gfx] [PATCH] drm/i915: Only wait one vblank when disabling crc if the pipe is on

[Daniel Vetter]

Otherwise we incur an unsightly WARNING. The mutex locking is a bit
overkill, but it curbs races and eventially we might grow a locking
check in the vblank wait code to make sure the right crtc lock is
held.

This is fallout from

commit 9393707190194eb8b42e412b444a03331db6862f
Author:     Jesse Barnes <jbarnes at virtuousgeek.org>
AuthorDate: Fri Apr 4 16:12:09 2014 -0700

    drm/i915: warn when a vblank wait times out

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=79612
Tested-by: Guo Jinxian <jinxianx.guo at intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 601caa88c092..cf94e9640627 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2927,11 +2927,16 @@ static int pipe_crc_set_source(struct drm_device *dev, enum pipe pipe,
 	/* real source -> none transition */
 	if (source == INTEL_PIPE_CRC_SOURCE_NONE) {
 		struct intel_pipe_crc_entry *entries;
+		struct intel_crtc *crtc =
+			crtc = to_intel_crtc(dev_priv->pipe_to_crtc_mapping[pipe]);
 
 		DRM_DEBUG_DRIVER("stopping CRCs for pipe %c\n",
 				 pipe_name(pipe));
 
-		intel_wait_for_vblank(dev, pipe);
+		mutex_lock(&crtc->base.mutex);
+		if (crtc->active)
+			intel_wait_for_vblank(dev, pipe);
+		mutex_unlock(&crtc->base.mutex);
 
 		spin_lock_irq(&pipe_crc->lock);
 		entries = pipe_crc->entries;
-- 
2.0.0