tests/kms_fbcon_fbt: Make FBC wait_until_update() more reliable

We can't depend onto debugfs reads of the FBC status as compression
takes one idle frame to recompress and we could easily miss that.

Instead lets use the pipe CRC as it keeps the CRC of each frame so we
can compare each other until a blink in the FBCON causes it do change.

Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index bf6be552..9e6c5c99 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -368,8 +368,17 @@ bool igt_debugfs_search(int device, const char *filename, const char *substring)
  * Pipe CRC
  */
 
-static bool igt_find_crc_mismatch(const igt_crc_t *a, const igt_crc_t *b,
-				  int *index)
+/**
+ * igt_find_crc_mismatch:
+ * @a: first pipe CRC value
+ * @b: second pipe CRC value
+ * @index: index of the first value that mismatched
+ *
+ * Check if CRC a and CRC b mismatch.
+ *
+ * Returns true if CRC values mismatch, false otherwise;
+ */
+bool igt_find_crc_mismatch(const igt_crc_t *a, const igt_crc_t *b, int *index)
 {
 	int nwords = min(a->n_words, b->n_words);
 	int i;