[Intel-gfx] [PATCH i-g-t 1/2] pipe_crc: Warn if the CRC values is 0xffffffff

[Damien Lespiau]

This is what we read when the CRC logic in in a powered down well. We
really don't want that to happen.

In theory, it's possible 0xffffffff to be a valid CRC value, so I don't
assert here.

Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
 lib/igt_debugfs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index 2f655a1..5c4bbc5 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -199,9 +199,14 @@ bool igt_crc_is_null(igt_crc_t *crc)
 {
 	int i;
 
-	for (i = 0; i < crc->n_words; i++)
+	for (i = 0; i < crc->n_words; i++) {
+		if (crc->crc[i] == 0xffffffff)
+			igt_warn("Suspicious CRC: it looks like the CRC "
+				 "read back was from a register in a powered "
+				 "down well\n");
 		if (crc->crc[i])
 			return false;
+	}
 
 	return true;
 }
-- 
1.8.3.1