[PATCH i-g-t v1] tests/intel/kms_pipe_stress: retry connectors with no modes and skip unusable pipes

[Sowmiya S <sowmiya.s@intel.com>]

Retry connectors with no probed modes up to 3 times (100ms intervals).
Skip connectors/pipes that remain unusable and clear connector entries.
Log skips using connector names (e.g. DP-5) to aid debugging.
Keep downstream state consistent so framebuffers/threads skip invalid pipes.

Signed-off-by: Sowmiya S <sowmiya.s@intel.com>
---
 tests/intel/kms_pipe_stress.c | 67 ++++++++++++++++++++++++++++++-----
 1 file changed, 58 insertions(+), 9 deletions(-)

diff --git a/tests/intel/kms_pipe_stress.c b/tests/intel/kms_pipe_stress.c
index 36e3842c6..1dc65b73c 100644
--- a/tests/intel/kms_pipe_stress.c
+++ b/tests/intel/kms_pipe_stress.c
@@ -15,6 +15,7 @@
 #include <string.h>
 #include <time.h>
 #include <poll.h>
+#include <unistd.h>
 #include <pthread.h>
 #include <semaphore.h>
 #include "i915/gem.h"
@@ -603,6 +604,7 @@ static void stress_pipes(struct data *data, struct timespec *start,
 
 #define MIN_DURATION_SEC 5.0
 #define MIN_ITERATIONS (igt_run_in_simulation() ? 5 : 20)
+#define MST_MODE_RETRY_COUNT 3
 
 static void stress(struct data *data)
 {
@@ -763,6 +765,7 @@ static void prepare_test(struct data *data)
 	int i, j;
 	int num_connectors;
 	int num_cpus = (int) sysconf(_SC_NPROCESSORS_ONLN);
+	bool any_pipe = false;
 
 	data->number_of_cores = min(num_cpus, MAX_CORES);
 
@@ -792,26 +795,62 @@ static void prepare_test(struct data *data)
 	for (i = 0; i < IGT_MAX_PIPES; i++) {
 		drmModeConnector *connector = (drmModeConnector *)data->connectors[i];
 		igt_crtc_t *crtc;
+		int retry;
 
 		if (!connector)
 			continue;
 
+		/*
+		 * MST connectors may appear connected before modes are
+		 * populated (HPD/topology settling).  Retry a few times
+		 * before giving up on this pipe.
+		 */
+		if (!connector->count_modes) {
+			uint32_t conn_id = connector->connector_id;
+
+			for (retry = 0; retry < MST_MODE_RETRY_COUNT; retry++) {
+				igt_info("Connector %s-%d has no modes yet "
+					 "(attempt %d/%d), retrying...\n",
+					 kmstest_connector_type_str(connector->connector_type),
+					 connector->connector_type_id,
+					 retry + 1, MST_MODE_RETRY_COUNT);
+				usleep(100 * 1000); /* 100 ms */
+				drmModeFreeConnector(connector);
+				connector = drmModeGetConnector(data->drm_fd, conn_id);
+				if (!connector)
+					break;
+				data->connectors[i] = connector;
+				if (connector->count_modes)
+					break;
+			}
+		}
+
+		if (!connector || connector->connection != DRM_MODE_CONNECTED ||
+		    !connector->count_modes) {
+			if (connector)
+				igt_info("Skipping connector %s-%d: not ready or no usable modes\n",
+					 kmstest_connector_type_str(connector->connector_type),
+					 connector->connector_type_id);
+			data->connectors[i] = NULL;
+			continue;
+		}
+
+		data->highest_mode[i] = find_highest_mode(connector);
 		if (!data->highest_mode[i]) {
-			if (connector->count_modes)
-				data->highest_mode[i] = find_highest_mode(connector);
+			igt_info("Connector %s-%d: find_highest_mode returned NULL, skipping\n",
+				 kmstest_connector_type_str(connector->connector_type),
+				 connector->connector_type_id);
+			data->connectors[i] = NULL;
+			continue;
 		}
-		igt_assert(data->highest_mode[i]);
 
 		crtc = igt_crtc_for_pipe(display, i);
 		if (!crtc)
 			continue;
 
-		if (data->highest_mode[i]) {
-			igt_info("Using mode: \n");
-			kmstest_dump_mode(data->highest_mode[i]);
-			data->pipe_crc[i] = igt_crtc_crc_new(crtc, IGT_PIPE_CRC_SOURCE_AUTO);
-		} else
-			data->pipe_crc[i] = NULL;
+		igt_info("Using mode:\n");
+		kmstest_dump_mode(data->highest_mode[i]);
+		data->pipe_crc[i] = igt_crtc_crc_new(crtc, IGT_PIPE_CRC_SOURCE_AUTO);
 
 		if (data->num_planes[i] == -1)
 			data->num_planes[i] = crtc->n_planes;
@@ -820,6 +859,16 @@ static void prepare_test(struct data *data)
 			 data->num_planes[i], i);
 	}
 
+	for (i = 0; i < IGT_MAX_PIPES; i++) {
+		if (data->highest_mode[i]) {
+			any_pipe = true;
+			break;
+		}
+		igt_require_f(any_pipe,
+			      "No pipes with usable display modes found "
+			      "(MST topology may still be settling)\n");
+	}
+
 	create_framebuffers(data);
 
 	if (intel_gen(intel_get_drm_devid(data->drm_fd)) > 9)
-- 
2.43.0