[PATCH i-g-t v4 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 it 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 | 39 +++++++++++++++++++++++++++++++++++++++
 lib/igt_kms.h |  3 +++
 2 files changed, 42 insertions(+)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index b3373435b252c9f8c5d5854f738f7f4bbc468964..d0b6c70f135754d0a413f73a0f8e5b24a208a2b3 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -7245,3 +7245,42 @@ double igt_default_display_detect_timeout(void)
 
 	return timeout;
 }
+
+/**
+ * igt_wait_for_connector_status:
+ * @drm_fd: drm file descriptor
+ * @connector_id: connector to monitor
+ * @timeout: maximum duration to wait, in second. Use -1.0 to set the timeout
+ *           to igt_default_detect_timeout().
+ * @drm_mode: mode to wait for, see enum drmModeConnection
+ *
+ * Wait for at most @timeout that the connector @connector_id  status
+ * become @drm_mode
+ * 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 == -1.0)
+		timeout = igt_default_display_detect_timeout();
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+	end = start;
+
+	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 91a26f2070efd26f9d107841ae3083b281d5e4c6..6d5582290f61d1a4151dd8e8448fc26c660a1536 100644
--- a/lib/igt_kms.h
+++ b/lib/igt_kms.h
@@ -1279,4 +1279,7 @@ int igt_backlight_write(int value, const char *fname, igt_backlight_context_t *c
 
 double igt_default_display_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__ */

-- 
2.47.1