[PATCH i-g-t 2/6] tests/intel/kms_mst_helper: Add helper for MST-related functions

[Jeevan B <jeevan.b@intel.com>]

From: Kunal Joshi <kunal1.joshi@intel.com>

This patch introduces kms_mst_helper.c and kms_mst_helper.h
to centralize commonly used MST-related logic.
The new function igt_find_all_mst_output_in_topology()
enumerates MST outputs that share the same root connector,
simplifying code reuse across tests needing outputs on
same MST topology. The existing MST-related code in
kms_dp_linktrain_fallback.c is updated to use the new helper,
removing duplication. Additionally, meson.build is modified
to include kms_mst_helper.c in the build process.

Signed-off-by: Kunal Joshi <kunal1.joshi@intel.com>
Reviewed-by: Jeevan B <jeevan.b@intel.com>
---
 tests/intel/kms_dp_linktrain_fallback.c | 28 +++------------
 tests/intel/kms_mst_helper.c            | 48 +++++++++++++++++++++++++
 tests/intel/kms_mst_helper.h            | 10 ++++++
 tests/meson.build                       |  1 +
 4 files changed, 63 insertions(+), 24 deletions(-)
 create mode 100644 tests/intel/kms_mst_helper.c
 create mode 100644 tests/intel/kms_mst_helper.h

diff --git a/tests/intel/kms_dp_linktrain_fallback.c b/tests/intel/kms_dp_linktrain_fallback.c
index 415005774..c409f9e9d 100644
--- a/tests/intel/kms_dp_linktrain_fallback.c
+++ b/tests/intel/kms_dp_linktrain_fallback.c
@@ -16,6 +16,7 @@
 #include <sys/types.h>
 #include "igt_sysfs.h"
 #include "igt.h"
+#include "kms_mst_helper.h"
 
 /**
  * SUBTEST: dp-fallback
@@ -47,28 +48,6 @@ typedef int (*condition_check_fn)(int drm_fd, igt_output_t *output);
 
 IGT_TEST_DESCRIPTION("Test link training fallback");
 
-static void find_mst_outputs(int drm_fd, data_t *data,
-			     igt_output_t *output,
-			     igt_output_t *mst_outputs[],
-			     int *num_mst_outputs)
-{
-	int output_root_id, root_id;
-	igt_output_t *connector_output;
-
-	output_root_id = igt_get_dp_mst_connector_id(output);
-	/*
-	 * If output is MST check all other connected output which shares
-	 * same path and fill mst_outputs and num_mst_outputs
-	 */
-	for_each_connected_output(&data->display, connector_output) {
-		if (!igt_check_output_is_dp_mst(connector_output))
-			continue;
-		root_id = igt_get_dp_mst_connector_id(connector_output);
-		if (((*num_mst_outputs) < IGT_MAX_PIPES) && root_id == output_root_id)
-			mst_outputs[(*num_mst_outputs)++] = connector_output;
-	}
-}
-
 static bool setup_mst_outputs(data_t *data, igt_output_t *mst_output[],
 			      int *output_count)
 {
@@ -83,8 +62,9 @@ static bool setup_mst_outputs(data_t *data, igt_output_t *mst_output[],
 		    traversed_mst_outputs[i] == data->output->config.connector->connector_id)
 			return false;
 
-	find_mst_outputs(data->drm_fd, data, data->output,
-			 mst_output, output_count);
+	igt_assert_f(igt_find_all_mst_output_in_topology(data->drm_fd, &data->display, data->output,
+							 mst_output, output_count),
+		     "Unable to find mst outputs\n");
 
 	for (i = 0; i < *output_count; i++) {
 		output = mst_output[i];
diff --git a/tests/intel/kms_mst_helper.c b/tests/intel/kms_mst_helper.c
new file mode 100644
index 000000000..9d52068f7
--- /dev/null
+++ b/tests/intel/kms_mst_helper.c
@@ -0,0 +1,48 @@
+#include "kms_mst_helper.h"
+
+/*
+ * @drm_fd: DRM file descriptor
+ * @display: pointer to an #igt_display_t structure
+ * @output: target output
+ * @mst_outputs: filled with mst output of same toplogy as @output
+ * @num_mst_outputs: filled with count of mst outputs found in topology
+ * @n_pipes: total number of pipes available
+ * @used_pipes_mask: pointer to a bitmask (in/out) of already-used pipes
+ * @master_pipes_mask: bitmask of valid "master" pipes
+ * @valid_pipes_mask: bitmask of valid (non-fused) pipes
+ *
+ * Assign pipes to outputs based on the number of required pipes.
+ * This function will assign 1, 2, or 4 consecutive pipes to each output.
+ * It will also mark the used pipes in the bitmask.
+ *
+ * Returns: true if all outputs can be assigned successfully; false otherwise.
+ */
+bool igt_find_all_mst_output_in_topology(int drm_fd, igt_display_t *display,
+					 igt_output_t *output,
+					 igt_output_t *mst_outputs[],
+					 int *num_mst_outputs)
+{
+	int output_root_id, root_id;
+	igt_output_t *connector_output;
+
+	if (!igt_check_output_is_dp_mst(output))
+		return false;
+
+	output_root_id = igt_get_dp_mst_connector_id(output);
+	if (output_root_id == -EINVAL)
+		return false;
+
+	/*
+	 * If output is MST, check all other connected output which shares
+	 * same path and fill mst_outputs and num_mst_outputs
+	 */
+	for_each_connected_output(display, connector_output) {
+		if (!igt_check_output_is_dp_mst(connector_output))
+			continue;
+
+		root_id = igt_get_dp_mst_connector_id(connector_output);
+		if (((*num_mst_outputs) < IGT_MAX_PIPES) && root_id == output_root_id)
+			mst_outputs[(*num_mst_outputs)++] = connector_output;
+	}
+	return true;
+}
diff --git a/tests/intel/kms_mst_helper.h b/tests/intel/kms_mst_helper.h
new file mode 100644
index 000000000..291fcebfe
--- /dev/null
+++ b/tests/intel/kms_mst_helper.h
@@ -0,0 +1,10 @@
+#ifndef KMS_MST_HELPER_H
+#define KMS_MST_HELPER_H
+
+#include "igt.h"
+
+bool igt_find_all_mst_output_in_topology(int drm_fd, igt_display_t *display,
+					 igt_output_t *output,
+					 igt_output_t *mst_outputs[],
+					 int *num_mst_outputs);
+#endif
diff --git a/tests/meson.build b/tests/meson.build
index 40e75b671..6e321649f 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -368,6 +368,7 @@ extra_sources = {
 	'kms_chamelium_hpd': [ join_paths ('chamelium', 'kms_chamelium_helper.c') ],
 	'kms_dsc': [ join_paths ('intel', 'kms_dsc_helper.c') ],
 	'kms_joiner': [join_paths ('intel', 'kms_joiner_helper.c')],
+	'kms_dp_linktrain_fallback': [join_paths ('intel', 'kms_mst_helper.c')],
 	'kms_psr2_sf':  [ join_paths ('intel', 'kms_dsc_helper.c') ],
 }
 
-- 
2.25.1