igt/kms_flip: Poll before reading from nonblocking drm_fd

If we run the full testsuite, the drm_fd is set to nonblocking - so we
have to explicitly wait using poll rather than rely on a blocking read
for the vblank event.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 1 insertions, 0 deletions

diff --git a/tests/kms_flip.c b/tests/kms_flip.c
index 76b1cc2b..fc946d36 100644
--- a/tests/kms_flip.c
+++ b/tests/kms_flip.c
@@ -1187,6 +1187,7 @@ static void calibrate_ts(struct test_output *o, int crtc_idx)
 		struct drm_event_vblank ev;
 		uint64_t now;
 
+		igt_assert(poll(&(struct pollfd){drm_fd, POLLIN}, 1, -1) == 1);
 		igt_assert(read(drm_fd, &ev, sizeof(ev)) == sizeof(ev));
 		igt_assert_eq(ev.sequence, last_seq + 1);