[PATCH i-g-t v3 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 | 39 +++++++++++++++++++++++++++++++++++++++
 lib/igt_kms.h |  3 +++
 2 files changed, 42 insertions(+)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index 0b76a47eb2135cca21881d97c2fd78e724d9a30e..626f56b8caa4bc0ba98c69aa22d0a6bf80aadedf 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -7218,3 +7218,42 @@ float igt_default_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_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 3509283b6da5b3fdbd70ebdc9bdd241326bc5073..6c6df3f18dde72459d09b56192e108da5d951bdd 100644
--- a/lib/igt_kms.h
+++ b/lib/igt_kms.h
@@ -1275,4 +1275,7 @@ int igt_backlight_write(int value, const char *fname, igt_backlight_context_t *c
 
 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__ */

-- 
2.47.0