Hi Vidya,

on which machines this would help? I see there's many vblanks already being waited. There's igt_display_commit2 which probably will block and even if it didn't there's igt_pipe_crc_collect_crc(..) where crc calculation is started after flip and then get one crc before disabling crc counting again.

/Juha-Pekka

On 21.5.2021 7.08, Vidya Srinivas wrote:
Without wait for vblank, CRC mismatch is seen
between big and small CRC on few systems

Change-Id: I3bec931aa901130997e693ac1cacf389e2a8100f
Signed-off-by: Vidya Srinivas <vidya.srini...@intel.com>
---
  tests/kms_big_fb.c | 6 ++++--
  1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tests/kms_big_fb.c b/tests/kms_big_fb.c
index b2027b6b9d1b..7d78ff829d41 100644
--- a/tests/kms_big_fb.c
+++ b/tests/kms_big_fb.c
@@ -254,6 +254,7 @@ static void unset_lut(data_t *data)
  static bool test_plane(data_t *data)
  {
        igt_plane_t *plane = data->plane;
+       igt_display_t *display = &data->display;
        struct igt_fb *small_fb = &data->small_fb;
        struct igt_fb *big_fb = &data->big_fb;
        int w = data->big_fb_width - small_fb->width;
@@ -337,16 +338,17 @@ static bool test_plane(data_t *data)
                igt_display_commit2(&data->display, data->display.is_atomic ?
                                    COMMIT_ATOMIC : COMMIT_UNIVERSAL);
-
+               igt_wait_for_vblank(data->drm_fd, 
display->pipes[data->pipe].crtc_offset);
                igt_pipe_crc_collect_crc(data->pipe_crc, &small_crc);
igt_plane_set_fb(plane, big_fb);
                igt_fb_set_position(big_fb, plane, x, y);
                igt_fb_set_size(big_fb, plane, small_fb->width, 
small_fb->height);
+
                igt_plane_set_size(plane, data->width, data->height);
                igt_display_commit2(&data->display, data->display.is_atomic ?
                                    COMMIT_ATOMIC : COMMIT_UNIVERSAL);
-
+               igt_wait_for_vblank(data->drm_fd, 
display->pipes[data->pipe].crtc_offset);
                igt_pipe_crc_collect_crc(data->pipe_crc, &big_crc);
igt_plane_set_fb(plane, NULL);


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