drm/i915: Replace nondescript 'WARN_ON(!lret)' with a sensible error message

When a vblank wait times out in intel_atomic_wait_for_vblanks() we just
get a cryptic 'WARN_ON(!ret)' backtrace in dmesg. Repace it with
something that tells you what actually happened.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460978973-24945-1-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index c5b9687091f44b21b2fa41fa66e65d3ab3d3ce42..68151271283ce1923b32dbd59221e48782929fde 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -13526,7 +13526,7 @@ static void intel_atomic_wait_for_vblanks(struct drm_device *dev,
                                        drm_crtc_vblank_count(crtc),
                                msecs_to_jiffies(50));
 
-               WARN_ON(!lret);
+               WARN(!lret, "pipe %c vblank wait timed out\n", pipe_name(pipe));
 
                drm_crtc_vblank_put(crtc);
        }