[PATCH i-g-t v2 2/5] lib/igt_kms: Add helper to wait for a specific status on a connector

[Louis Chauvet]

During testing with chamelium, it is frequent to wait for a specific
connector status. This new helper is polling the DRM API to wait for this
status. This allows detecting new status without notifier systems (which
can fail if hot plug detection is not working properly on the device under
test.

Signed-off-by: Louis Chauvet <louis.chauvet at bootlin.com>
---
 lib/igt_kms.c | 38 ++++++++++++++++++++++++++++++++++++++
 lib/igt_kms.h |  3 +++
 2 files changed, 41 insertions(+)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index 195868646a14..40c0a207cd17 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -7143,3 +7143,41 @@ float igt_default_detect_timeout(void)
 
 	return timeout;
 }
+
+/**
+ * igt_wait_for_connector_status - Wait for at most @timeout that the connector @connector_id
+ * status become @drm_mode
+ *
+ * @drm_fd: drm file descriptor
+ * @connector_id: connector to monitor
+ * @timeout: maximum duration to wait, in second
+ * @drm_mode: mode to wait for, see enum drmModeConnection
+ *
+ * Returns: true when the status is reached, false if there is a timeout
+ */
+bool igt_wait_for_connector_status(int drm_fd, unsigned int connector_id, double timeout,
+				   int drm_mode)
+{
+	drmModeConnector *connector;
+	struct timespec start, end;
+
+	if (timeout == 0.0)
+		timeout = igt_default_detect_timeout();
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+	clock_gettime(CLOCK_MONOTONIC, &end);
+
+	while (igt_time_elapsed(&start, &end) <= timeout) {
+		connector = drmModeGetConnector(drm_fd, connector_id);
+		if (connector && connector->connection == drm_mode) {
+			free(connector);
+			return true;
+		}
+		free(connector);
+		clock_gettime(CLOCK_MONOTONIC, &end);
+	}
+
+	igt_debug("Timeout waiting for connection status %d on connector %d\n", drm_mode,
+		  connector_id);
+	return false;
+}
diff --git a/lib/igt_kms.h b/lib/igt_kms.h
index 4f0030264d9f..4cd4a4f65460 100644
--- a/lib/igt_kms.h
+++ b/lib/igt_kms.h
@@ -1263,4 +1263,7 @@ void igt_reset_link_params(int drm_fd, igt_output_t *output);
 
 float igt_default_detect_timeout(void);
 
+bool igt_wait_for_connector_status(int drm_fd, unsigned int connector_id, double timeout,
+				   int drm_mode);
+
 #endif /* __IGT_KMS_H__ */

-- 
2.46.2