[igt-dev] [v5 i-g-t 04/14] tests/debugfs_test: Fix mode selection for MST

[Bhanuprakash Modem]

When two monitors connected through MST, the second monitor also
tries to use the same mode. So two such modes may not fit into the
link bandwidth.

This patch will find a combination of modes that fit into the BW.

V2:
* Add support for legacy commit (Ankit)

Cc: Imre Deak <imre.deak at intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
---
 tests/debugfs_test.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tests/debugfs_test.c b/tests/debugfs_test.c
index 46ba0a8be..e50f213ae 100644
--- a/tests/debugfs_test.c
+++ b/tests/debugfs_test.c
@@ -98,12 +98,14 @@ static void kms_tests(int fd, int debugfs)
 	igt_display_t display;
 	struct igt_fb fb[IGT_MAX_PIPES];
 	enum pipe pipe;
+	int ret;
 
 	igt_fixture
 		igt_display_require(&display, fd);
 
 	igt_subtest("read_all_entries_display_on") {
 		/* try to light all pipes */
+retry:
 		for_each_pipe(&display, pipe) {
 			igt_output_t *output;
 
@@ -128,6 +130,25 @@ static void kms_tests(int fd, int debugfs)
 			}
 		}
 
+		if (display.is_atomic)
+			ret = igt_display_try_commit_atomic(&display,
+					DRM_MODE_ATOMIC_TEST_ONLY |
+					DRM_MODE_ATOMIC_ALLOW_MODESET,
+					NULL);
+		else
+			ret = igt_display_try_commit2(&display, COMMIT_LEGACY);
+
+		if (ret) {
+			igt_output_t *output;
+			bool found = igt_override_all_active_output_modes_to_fit_bw(&display);
+			igt_require_f(found, "No valid mode combo found.\n");
+
+			for_each_connected_output(&display, output)
+				igt_output_set_pipe(output, PIPE_NONE);
+
+			goto retry;
+		}
+
 		igt_display_commit2(&display, display.is_atomic ? COMMIT_ATOMIC : COMMIT_LEGACY);
 
 		read_and_discard_sysfs_entries(debugfs, 0);
-- 
2.20.1