drm/amd/display: Add DP 2.0 MST DC Support

[Why]
configure/call DC interface for DP2 mst support. This is needed to make DP2
mst work.

[How]
- add encoding type, logging, mst update/reduce payload functions

Use the link encoding to determine the DP type (1.4 or 2.0) and add a
flag to dc_stream_update to determine whether to increase/reduce
payloads.

v2:
* add DP_UNKNOWN_ENCODING handling
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Reviewed-by: "Lin, Wayne" <Wayne.Lin@amd.com>
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211025223825.301703-4-lyude@redhat.com

drivers/gpu/drm/amd/display/dc/core/dc.c

@@ -2356,6 +2356,11 @@ static enum surface_update_type check_update_surfaces_for_stream(
 		if (stream_update->dsc_config)
 			su_flags->bits.dsc_changed = 1;
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+		if (stream_update->mst_bw_update)
+			su_flags->bits.mst_bw = 1;
+#endif
+
 		if (su_flags->raw != 0)
 			overall_type = UPDATE_TYPE_FULL;
 
@@ -2741,6 +2746,15 @@ static void commit_planes_do_stream_update(struct dc *dc,
 			if (stream_update->dsc_config)
 				dp_update_dsc_config(pipe_ctx);
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+			if (stream_update->mst_bw_update) {
+				if (stream_update->mst_bw_update->is_increase)
+					dc_link_increase_mst_payload(pipe_ctx, stream_update->mst_bw_update->mst_stream_bw);
+				else
+					dc_link_reduce_mst_payload(pipe_ctx, stream_update->mst_bw_update->mst_stream_bw);
+			}
+#endif
+
 			if (stream_update->pending_test_pattern) {
 				dc_link_dp_set_test_pattern(stream->link,
 					stream->test_pattern.type,

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

@@ -5993,6 +5993,25 @@ enum dp_link_encoding dp_get_link_encoding_format(const struct dc_link_settings
 }
 
 #if defined(CONFIG_DRM_AMD_DC_DCN)
+enum dp_link_encoding dc_link_dp_mst_decide_link_encoding_format(const struct dc_link *link)
+{
+	struct dc_link_settings link_settings = {0};
+
+	if (!dc_is_dp_signal(link->connector_signal))
+		return DP_UNKNOWN_ENCODING;
+
+	if (link->preferred_link_setting.lane_count !=
+			LANE_COUNT_UNKNOWN &&
+			link->preferred_link_setting.link_rate !=
+					LINK_RATE_UNKNOWN) {
+		link_settings = link->preferred_link_setting;
+	} else {
+		decide_mst_link_settings(link, &link_settings);
+	}
+
+	return dp_get_link_encoding_format(&link_settings);
+}
+
 // TODO - DP2.0 Link: Fix get_lane_status to handle LTTPR offset (SST and MST)
 static void get_lane_status(
 	struct dc_link *link,

drivers/gpu/drm/amd/display/dc/dc_link.h

@@ -296,6 +296,10 @@ enum dc_detect_reason {
 bool dc_link_detect(struct dc_link *dc_link, enum dc_detect_reason reason);
 bool dc_link_get_hpd_state(struct dc_link *dc_link);
 enum dc_status dc_link_allocate_mst_payload(struct pipe_ctx *pipe_ctx);
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+enum dc_status dc_link_reduce_mst_payload(struct pipe_ctx *pipe_ctx, uint32_t req_pbn);
+enum dc_status dc_link_increase_mst_payload(struct pipe_ctx *pipe_ctx, uint32_t req_pbn);
+#endif
 
 /* Notify DC about DP RX Interrupt (aka Short Pulse Interrupt).
  * Return:
@@ -425,4 +429,7 @@ uint32_t dc_bandwidth_in_kbps_from_timing(
 bool dc_link_is_fec_supported(const struct dc_link *link);
 bool dc_link_should_enable_fec(const struct dc_link *link);
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+enum dp_link_encoding dc_link_dp_mst_decide_link_encoding_format(const struct dc_link *link);
+#endif
 #endif /* DC_LINK_H_ */

drivers/gpu/drm/amd/display/dc/dc_stream.h

@@ -115,6 +115,13 @@ struct periodic_interrupt_config {
 	int lines_offset;
 };
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+struct dc_mst_stream_bw_update {
+	bool is_increase; // is bandwidth reduced or increased
+	uint32_t mst_stream_bw; // new mst bandwidth in kbps
+};
+#endif
+
 union stream_update_flags {
 	struct {
 		uint32_t scaling:1;
@@ -125,6 +132,9 @@ union stream_update_flags {
 		uint32_t gamut_remap:1;
 		uint32_t wb_update:1;
 		uint32_t dsc_changed : 1;
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+		uint32_t mst_bw : 1;
+#endif
 	} bits;
 
 	uint32_t raw;
@@ -278,6 +288,9 @@ struct dc_stream_update {
 
 	struct dc_writeback_update *wb_update;
 	struct dc_dsc_config *dsc_config;
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+	struct dc_mst_stream_bw_update *mst_bw_update;
+#endif
 	struct dc_transfer_func *func_shaper;
 	struct dc_3dlut *lut3d_func;