[PATCH 3/3] present: Check for an invalid target CRTC before flipping

[Chris Wilson]

Once we have chosen the target CRTC, check for an error when querying
the current MSC so we can report the error before attempting to record
the uninitialised MSC/UST, and subsequently feeding garbage values to
drmWaitVBlank.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 present/present.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/present/present.c b/present/present.c
index 1ce587e..4a1cf0c 100644
--- a/present/present.c
+++ b/present/present.c
@@ -727,7 +727,9 @@ present_pixmap(WindowPtr window,
     else if (!target_crtc)
 	target_crtc = present_get_crtc(window);
 
-    present_get_ust_msc(screen, target_crtc, &ust, &crtc_msc);
+    ret = present_get_ust_msc(screen, target_crtc, &ust, &crtc_msc);
+    if (ret)
+	    return ret;
 
     target_msc = present_window_to_crtc_msc(window, target_crtc, window_msc, crtc_msc);
 
-- 
2.1.4