drm/amdgpu/display: create fake mst encoders ahead of time (v4)

Prevents a warning in the MST create connector case.

v2: create global fake encoders rather per connector fake encoders
to avoid running out of encoder indices.

v3: use the actual number of crtcs on the asic rather than the max
to conserve encoders.

v4: v3 plus missing hunk I forgot to git add.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1108
Fixes: c6385e50 ("drm/amdgpu: drop legacy drm load and unload callbacks")
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org # 5.7.x

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -974,6 +974,9 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 	/* Update the actual used number of crtc */
 	adev->mode_info.num_crtc = adev->dm.display_indexes_num;
 
+	/* create fake encoders for MST */
+	dm_dp_create_fake_mst_encoders(adev);
+
 	/* TODO: Add_display_info? */
 
 	/* TODO use dynamic cursor width */
@@ -997,6 +1000,12 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 
 static void amdgpu_dm_fini(struct amdgpu_device *adev)
 {
+	int i;
+
+	for (i = 0; i < adev->dm.display_indexes_num; i++) {
+		drm_encoder_cleanup(&adev->dm.mst_encoders[i].base);
+	}
+
 	amdgpu_dm_audio_fini(adev);
 
 	amdgpu_dm_destroy_drm_device(&adev->dm);

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

@@ -43,6 +43,9 @@
  */
 
 #define AMDGPU_DM_MAX_DISPLAY_INDEX 31
+
+#define AMDGPU_DM_MAX_CRTC 6
+
 /*
 #include "include/amdgpu_dal_power_if.h"
 #include "amdgpu_dm_irq.h"
@@ -328,6 +331,13 @@ struct amdgpu_display_manager {
 	 * available in FW
 	 */
 	const struct gpu_info_soc_bounding_box_v1_0 *soc_bounding_box;
+
+	/**
+	 * @mst_encoders:
+	 *
+	 * fake encoders used for DP MST.
+	 */
+	struct amdgpu_encoder mst_encoders[AMDGPU_DM_MAX_CRTC];
 };
 
 struct amdgpu_dm_connector {
@@ -356,7 +366,6 @@ struct amdgpu_dm_connector {
 	struct amdgpu_dm_dp_aux dm_dp_aux;
 	struct drm_dp_mst_port *port;
 	struct amdgpu_dm_connector *mst_port;
-	struct amdgpu_encoder *mst_encoder;
 	struct drm_dp_aux *dsc_aux;
 
 	/* TODO see if we can merge with ddc_bus or make a dm_connector */

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c

@@ -95,7 +95,6 @@ dm_dp_mst_connector_destroy(struct drm_connector *connector)
 {
 	struct amdgpu_dm_connector *aconnector =
 		to_amdgpu_dm_connector(connector);
-	struct amdgpu_encoder *amdgpu_encoder = aconnector->mst_encoder;
 
 	if (aconnector->dc_sink) {
 		dc_link_remove_remote_sink(aconnector->dc_link,
@@ -105,8 +104,6 @@ dm_dp_mst_connector_destroy(struct drm_connector *connector)
 
 	kfree(aconnector->edid);
 
-	drm_encoder_cleanup(&amdgpu_encoder->base);
-	kfree(amdgpu_encoder);
 	drm_connector_cleanup(connector);
 	drm_dp_mst_put_port_malloc(aconnector->port);
 	kfree(aconnector);
@@ -243,7 +240,11 @@ static struct drm_encoder *
 dm_mst_atomic_best_encoder(struct drm_connector *connector,
 			   struct drm_connector_state *connector_state)
 {
-	return &to_amdgpu_dm_connector(connector)->mst_encoder->base;
+	struct drm_device *dev = connector->dev;
+	struct amdgpu_device *adev = dev->dev_private;
+	struct amdgpu_crtc *acrtc = to_amdgpu_crtc(connector_state->crtc);
+
+	return &adev->dm.mst_encoders[acrtc->crtc_id].base;
 }
 
 static int
@@ -306,19 +307,16 @@ static const struct drm_encoder_funcs amdgpu_dm_encoder_funcs = {
 	.destroy = amdgpu_dm_encoder_destroy,
 };
 
-static struct amdgpu_encoder *
-dm_dp_create_fake_mst_encoder(struct amdgpu_dm_connector *connector)
+void
+dm_dp_create_fake_mst_encoders(struct amdgpu_device *adev)
 {
-	struct drm_device *dev = connector->base.dev;
-	struct amdgpu_device *adev = dev->dev_private;
-	struct amdgpu_encoder *amdgpu_encoder;
-	struct drm_encoder *encoder;
+	struct drm_device *dev = adev->ddev;
+	int i;
 
-	amdgpu_encoder = kzalloc(sizeof(*amdgpu_encoder), GFP_KERNEL);
-	if (!amdgpu_encoder)
-		return NULL;
+	for (i = 0; i < adev->dm.display_indexes_num; i++) {
+		struct amdgpu_encoder *amdgpu_encoder = &adev->dm.mst_encoders[i];
+		struct drm_encoder *encoder = &amdgpu_encoder->base;
 
-	encoder = &amdgpu_encoder->base;
 		encoder->possible_crtcs = amdgpu_dm_get_encoder_crtc_mask(adev);
 
 		drm_encoder_init(
@@ -329,8 +327,7 @@ dm_dp_create_fake_mst_encoder(struct amdgpu_dm_connector *connector)
 			NULL);
 
 		drm_encoder_helper_add(encoder, &amdgpu_dm_encoder_helper_funcs);
-
-	return amdgpu_encoder;
+	}
 }
 
 static struct drm_connector *
@@ -343,6 +340,7 @@ dm_dp_add_mst_connector(struct drm_dp_mst_topology_mgr *mgr,
 	struct amdgpu_device *adev = dev->dev_private;
 	struct amdgpu_dm_connector *aconnector;
 	struct drm_connector *connector;
+	int i;
 
 	aconnector = kzalloc(sizeof(*aconnector), GFP_KERNEL);
 	if (!aconnector)
@@ -369,9 +367,10 @@ dm_dp_add_mst_connector(struct drm_dp_mst_topology_mgr *mgr,
 		master->dc_link,
 		master->connector_id);
 
-	aconnector->mst_encoder = dm_dp_create_fake_mst_encoder(master);
+	for (i = 0; i < adev->dm.display_indexes_num; i++) {
 		drm_connector_attach_encoder(&aconnector->base,
-				     &aconnector->mst_encoder->base);
+					     &adev->dm.mst_encoders[i].base);
+	}
 
 	connector->max_bpc_property = master->base.max_bpc_property;
 	if (connector->max_bpc_property)

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.h

@@ -35,6 +35,9 @@ void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm,
 				       struct amdgpu_dm_connector *aconnector,
 				       int link_index);
 
+void
+dm_dp_create_fake_mst_encoders(struct amdgpu_device *adev);
+
 #if defined(CONFIG_DRM_AMD_DC_DCN)
 bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
 				       struct dc_state *dc_state);