drm/i915/mst: Reject modes that require the bigjoiner

We have no bigjoiner support in the MST code, so .mode_valid()
pretending otherwise is just going to result black screens for
users. Reject any mode that needs the joiner.

Cc: [email protected]
Cc: Stanislav Lisovskiy <[email protected]>
Fixes: d51f25e ("drm/i915: Add DSC support to MST path")
Signed-off-by: Ville Syrjälä <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Reviewed-by: Jani Nikula <[email protected]>
(cherry picked from commit 9c05849)
Signed-off-by: Jani Nikula <[email protected]>

Author: vsyrjala

drivers/gpu/drm/i915/display/intel_dp_mst.c

@@ -997,6 +997,10 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
 	if (intel_dp_need_bigjoiner(intel_dp, mode->hdisplay, target_clock)) {
 		bigjoiner = true;
 		max_dotclk *= 2;
+
+		/* TODO: add support for bigjoiner */
+		*status = MODE_CLOCK_HIGH;
+		return 0;
 	}
 
 	if (DISPLAY_VER(dev_priv) >= 10 &&