kms_rotation_crc: Document the two steps in prepare_crtc()

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>

diff --git a/tests/kms_rotation_crc.c b/tests/kms_rotation_crc.c
index 5780e40..cb1b00b 100644 (file)
--- a/tests/kms_rotation_crc.c
+++ b/tests/kms_rotation_crc.c
@@ -104,14 +104,19 @@ static bool prepare_crtc(data_t *data, igt_output_t *output, enum pipe pipe,
                        &data->fb);
        igt_assert(fb_id);
 
+       /* Step 1: create a reference CRC for a software-rotated fb */
+
        paint_squares(data, &data->fb, mode, DRM_ROTATE_180);
 
        igt_plane_set_fb(plane, &data->fb);
        igt_display_commit(display);
 
-       /* Collect reference crc */
        igt_pipe_crc_collect_crc(data->pipe_crc, &data->ref_crc);
 
+       /*
+        * Step 2: prepare the plane with an non-rotated fb let the hw
+        * rotate it.
+        */
        paint_squares(data, &data->fb, mode, DRM_ROTATE_0);
 
        igt_plane_set_fb(plane, &data->fb);