[PATCH 6/6] drm/amdgpu/dm/mst: Use drm_dp_mst_connector_atomic_check()

[Lyude Paul <lyude@redhat.com>]

Hook this into amdgpu's atomic check for their connectors so they never
get modesets on no-longer-present MST connectors. We'll also expand on
this later once we add DP MST fallback retraining support.

As well, turns out that the only atomic DRM driver without the
->best_encoder() bug is amdgpu. Congrats AMD!

Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 .../drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c  | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 9a300732ba37..d011a39f17b2 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -294,10 +294,22 @@ static struct drm_encoder *dm_mst_best_encoder(struct drm_connector *connector)
 	return &amdgpu_dm_connector->mst_encoder->base;
 }
 
+static int
+amdgpu_dm_mst_connector_atomic_check(struct drm_connector *connector,
+				     struct drm_connector_state *new_cstate)
+{
+	struct amdgpu_dm_connector *aconnector =
+		to_amdgpu_dm_connector(connector);
+
+	return drm_dp_mst_connector_atomic_check(connector, new_cstate,
+						 &aconnector->mst_mgr);
+}
+
 static const struct drm_connector_helper_funcs dm_dp_mst_connector_helper_funcs = {
 	.get_modes = dm_dp_mst_get_modes,
 	.mode_valid = amdgpu_dm_connector_mode_valid,
 	.best_encoder = dm_mst_best_encoder,
+	.atomic_check = amdgpu_dm_mst_connector_atomic_check,
 };
 
 static void amdgpu_dm_encoder_destroy(struct drm_encoder *encoder)
-- 
2.17.1