kms_frontbuffer_tracking: refactor sink CRC reliability handling

What I'm currently seeing is that sometimes the first check during
setup_sink_crc() returns valid sink CRC, but then the subsequent
checks return ETIMEDOUT. In these cases, we keep getting flooded by
messages saying that our sink CRC is unreliable and that the results
differ. This is annoying for the FBC tests where sink CRC is not
mandatory.

Since this case shows it's useless to try to check for sink CRC
reliability before the actual tests, refactor the code in a way that
if at any point we detect that sink CRC is unreliable we'll mark it as
such and stop flooding the logs. For the tests where it's mandatory
we'll still keep the same SKIP behavior.

This refactor also allows us to just call get_sink_crc() in the
setup_sink_crc() function instead of having to reimplement the same
logic.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>

1 files changed, 18 insertions, 21 deletions

diff --git a/tests/kms_frontbuffer_tracking.c b/tests/kms_frontbuffer_tracking.c
index 4b16c2c9..c2ac9afd 100644
--- a/tests/kms_frontbuffer_tracking.c
+++ b/tests/kms_frontbuffer_tracking.c
@@ -203,9 +203,11 @@ struct both_crcs *wanted_crc;
 struct {
 	int fd;
 	bool supported;
+	bool reliable;
 } sink_crc = {
 	.fd = -1,
-	.supported = false,
+	.supported = true,
+	.reliable = true,
 };
 
 /* The goal of this structure is to easily allow us to deal with cases where we
@@ -943,11 +945,17 @@ static void get_sink_crc(sink_crc_t *crc, bool mandatory)
 	rc = read(sink_crc.fd, crc->data, SINK_CRC_SIZE);
 	errno_ = errno;
 
-	if (rc == -1 && errno_ == ETIMEDOUT) {
+	if (rc == -1 && errno_ == ENOTTY) {
+		igt_info("Sink CRC not supported: panel doesn't support it\n");
+		sink_crc.supported = false;
+	} else if (rc == -1 && errno_ == ETIMEDOUT) {
+		if (sink_crc.reliable) {
+			igt_info("Sink CRC is unreliable on this machine.\n");
+			sink_crc.reliable = false;
+		}
+
 		if (mandatory)
-			igt_skip("Sink CRC is unreliable on this machine. Try running this test again individually\n");
-		else
-			igt_info("Sink CRC is unreliable on this machine. Try running this test again individually\n");
+			igt_skip("Sink CRC is unreliable on this machine.\n");
 	} else {
 		igt_assert(rc == SINK_CRC_SIZE);
 	}
@@ -1396,9 +1404,7 @@ static void teardown_modeset(void)
 
 static void setup_sink_crc(void)
 {
-	ssize_t rc;
 	sink_crc_t crc;
-	int errno_;
 	drmModeConnectorPtr c;
 
 	c = get_connector(prim_mode_params.connector_id);
@@ -1418,17 +1424,8 @@ static void setup_sink_crc(void)
 	sink_crc.fd = igt_debugfs_open("i915_sink_crc_eDP1", O_RDONLY);
 	igt_assert_lte(0, sink_crc.fd);
 
-	rc = read(sink_crc.fd, crc.data, SINK_CRC_SIZE);
-	errno_ = errno;
-	if (rc == -1 && errno_ == ENOTTY)
-		igt_info("Sink CRC not supported: panel doesn't support it\n");
-	if (rc == -1 && errno_ == ETIMEDOUT)
-		igt_info("Sink CRC not reliable on this panel: skipping it\n");
-	else if (rc == SINK_CRC_SIZE)
-		sink_crc.supported = true;
-	else
-		igt_info("Unexpected sink CRC error, rc=:%zd errno:%d %s\n",
-			 rc, errno_, strerror(errno_));
+	/* Do a first read to try to detect if it's supported. */
+	get_sink_crc(&crc, false);
 }
 
 static void setup_crcs(void)
@@ -1677,9 +1674,9 @@ static int adjust_assertion_flags(const struct test_mode *t, int flags)
 	igt_assert_crc_equal(&crc_.pipe, &wanted_crc->pipe);		\
 	if (mandatory_sink_crc)						\
 		assert_sink_crc_equal(&crc_.sink, &wanted_crc->sink);	\
-	else								\
-		if (!sink_crc_equal(&crc_.sink, &wanted_crc->sink))	\
-			igt_info("Sink CRC differ, but not required\n"); \
+	else if (sink_crc.reliable &&					\
+		 !sink_crc_equal(&crc_.sink, &wanted_crc->sink))	\
+		igt_info("Sink CRC differ, but not required\n"); 	\
 } while (0)
 
 #define do_status_assertions(flags_) do {				\