[igt-dev] [PATCH i-g-t] tests/i915/kms_cdclk: Fixed mode selection for MST modeset

[Mohammed Thasleem]

Added check on ENOSPC and EINVAL, when two monitors connected
through MST. This will find the connector mode combo that
fits into the bandwidth when more than one monitor is connected.

Example:
  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. So, iterate through connected
  outputs & modes and find a combination of modes those fit
  into the link BW.

Signed-off-by: Mohammed Thasleem <mohammed.thasleem at intel.com>
---
 tests/i915/kms_cdclk.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tests/i915/kms_cdclk.c b/tests/i915/kms_cdclk.c
index 991a7c507..04f39bea5 100644
--- a/tests/i915/kms_cdclk.c
+++ b/tests/i915/kms_cdclk.c
@@ -313,7 +313,16 @@ static void test_mode_transition_on_all_outputs(data_t *data)
 		j++;
 	}
 
+	/* In case of DP-MST find suitable mode(s) to fit into the link BW. */
+	if ((igt_display_try_commit_atomic(display, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL) != 0) &&
+	    (errno == EINVAL || errno == ENOSPC)) {
+		bool found = igt_override_all_active_output_modes_to_fit_bw(display);
+
+		igt_require_f(found, "No valid mode combo found for MST modeset.\n");
+	}
+
 	igt_display_commit2(display, COMMIT_ATOMIC);
+
 	cdclk_new = get_current_cdclk_freq(debugfs_fd);
 	igt_info("CD clock frequency %d -> %d\n", cdclk_ref, cdclk_new);
 
-- 
2.25.1