Revert "drm/amd/display: Refactor function dm_dp_mst_is_port_support_mode()"

This reverts commit 6b2fb172853261829229237766d078638267042f which is
commit fa57924c76d995e87ca3533ec60d1d5e55769a27 upstream.

It breaks the build on arm64 and arm systems, and trying to unwind the
ifdef mess to fix it up was not simple at all.  So revert it and wait
for a fixed change to come back.

Cc: Jerry Zuo <jerry.zuo@amd.com>
Cc: Zaeem Mohamed <zaeem.mohamed@amd.com>
Cc: Wayne Lin <wayne.lin@amd.com>
Cc: Daniel Wheeler <daniel.wheeler@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Kevin Holm <kevin@holm.dev>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/b27c5434-f1b1-4697-985b-91bb3e9a22df@roeck-us.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 85 insertions, 147 deletions

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 bb4e5ab7edc6..b50010ed7633 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
@@ -1594,171 +1594,109 @@ static bool is_dsc_common_config_possible(struct dc_stream_state *stream,
 	return bw_range->max_target_bpp_x16 && bw_range->min_target_bpp_x16;
 }
 
-#if defined(CONFIG_DRM_AMD_DC_FP)
-static bool dp_get_link_current_set_bw(struct drm_dp_aux *aux, uint32_t *cur_link_bw)
-{
-	uint32_t total_data_bw_efficiency_x10000 = 0;
-	uint32_t link_rate_per_lane_kbps = 0;
-	enum dc_link_rate link_rate;
-	union lane_count_set lane_count;
-	u8 dp_link_encoding;
-	u8 link_bw_set = 0;
-
-	*cur_link_bw = 0;
-
-	if (drm_dp_dpcd_read(aux, DP_MAIN_LINK_CHANNEL_CODING_SET, &dp_link_encoding, 1) != 1 ||
-		drm_dp_dpcd_read(aux, DP_LANE_COUNT_SET, &lane_count.raw, 1) != 1 ||
-		drm_dp_dpcd_read(aux, DP_LINK_BW_SET, &link_bw_set, 1) != 1)
-		return false;
-
-	switch (dp_link_encoding) {
-	case DP_8b_10b_ENCODING:
-		link_rate = link_bw_set;
-		link_rate_per_lane_kbps = link_rate * LINK_RATE_REF_FREQ_IN_KHZ * BITS_PER_DP_BYTE;
-		total_data_bw_efficiency_x10000 = DATA_EFFICIENCY_8b_10b_x10000;
-		total_data_bw_efficiency_x10000 /= 100;
-		total_data_bw_efficiency_x10000 *= DATA_EFFICIENCY_8b_10b_FEC_EFFICIENCY_x100;
-		break;
-	case DP_128b_132b_ENCODING:
-		switch (link_bw_set) {
-		case DP_LINK_BW_10:
-			link_rate = LINK_RATE_UHBR10;
-			break;
-		case DP_LINK_BW_13_5:
-			link_rate = LINK_RATE_UHBR13_5;
-			break;
-		case DP_LINK_BW_20:
-			link_rate = LINK_RATE_UHBR20;
-			break;
-		default:
-			return false;
-		}
-
-		link_rate_per_lane_kbps = link_rate * 10000;
-		total_data_bw_efficiency_x10000 = DATA_EFFICIENCY_128b_132b_x10000;
-		break;
-	default:
-		return false;
-	}
-
-	*cur_link_bw = link_rate_per_lane_kbps * lane_count.bits.LANE_COUNT_SET / 10000 * total_data_bw_efficiency_x10000;
-	return true;
-}
-#endif
-
 enum dc_status dm_dp_mst_is_port_support_mode(
 	struct amdgpu_dm_connector *aconnector,
 	struct dc_stream_state *stream)
 {
-#if defined(CONFIG_DRM_AMD_DC_FP)
-	int branch_max_throughput_mps = 0;
+	int pbn, branch_max_throughput_mps = 0;
 	struct dc_link_settings cur_link_settings;
-	uint32_t end_to_end_bw_in_kbps = 0;
-	uint32_t root_link_bw_in_kbps = 0;
-	uint32_t virtual_channel_bw_in_kbps = 0;
+	unsigned int end_to_end_bw_in_kbps = 0;
+	unsigned int upper_link_bw_in_kbps = 0, down_link_bw_in_kbps = 0;
 	struct dc_dsc_bw_range bw_range = {0};
 	struct dc_dsc_config_options dsc_options = {0};
-	uint32_t stream_kbps;
 
-	/* DSC unnecessary case
-	 * Check if timing could be supported within end-to-end BW
+	/*
+	 * Consider the case with the depth of the mst topology tree is equal or less than 2
+	 * A. When dsc bitstream can be transmitted along the entire path
+	 *    1. dsc is possible between source and branch/leaf device (common dsc params is possible), AND
+	 *    2. dsc passthrough supported at MST branch, or
+	 *    3. dsc decoding supported at leaf MST device
+	 *    Use maximum dsc compression as bw constraint
+	 * B. When dsc bitstream cannot be transmitted along the entire path
+	 *    Use native bw as bw constraint
 	 */
-	stream_kbps =
-		dc_bandwidth_in_kbps_from_timing(&stream->timing,
-			dc_link_get_highest_encoding_format(stream->link));
-	cur_link_settings = stream->link->verified_link_cap;
-	root_link_bw_in_kbps = dc_link_bandwidth_kbps(aconnector->dc_link, &cur_link_settings);
-	virtual_channel_bw_in_kbps = kbps_from_pbn(aconnector->mst_output_port->full_pbn);
-
-	/* pick the end to end bw bottleneck */
-	end_to_end_bw_in_kbps = min(root_link_bw_in_kbps, virtual_channel_bw_in_kbps);
-
-	if (stream_kbps <= end_to_end_bw_in_kbps) {
-		DRM_DEBUG_DRIVER("No DSC needed. End-to-end bw sufficient.");
-		return DC_OK;
-	}
-
-	/*DSC necessary case*/
-	if (!aconnector->dsc_aux)
-		return DC_FAIL_BANDWIDTH_VALIDATE;
-
-	if (is_dsc_common_config_possible(stream, &bw_range)) {
-
-		/*capable of dsc passthough. dsc bitstream along the entire path*/
-		if (aconnector->mst_output_port->passthrough_aux) {
-			if (bw_range.min_kbps > end_to_end_bw_in_kbps) {
-				DRM_DEBUG_DRIVER("DSC passthrough. Max dsc compression can't fit into end-to-end bw\n");
+	if (is_dsc_common_config_possible(stream, &bw_range) &&
+	   (aconnector->mst_output_port->passthrough_aux ||
+	    aconnector->dsc_aux == &aconnector->mst_output_port->aux)) {
+		cur_link_settings = stream->link->verified_link_cap;
+		upper_link_bw_in_kbps = dc_link_bandwidth_kbps(aconnector->dc_link, &cur_link_settings);
+		down_link_bw_in_kbps = kbps_from_pbn(aconnector->mst_output_port->full_pbn);
+
+		/* pick the end to end bw bottleneck */
+		end_to_end_bw_in_kbps = min(upper_link_bw_in_kbps, down_link_bw_in_kbps);
+
+		if (end_to_end_bw_in_kbps < bw_range.min_kbps) {
+			DRM_DEBUG_DRIVER("maximum dsc compression cannot fit into end-to-end bandwidth\n");
 			return DC_FAIL_BANDWIDTH_VALIDATE;
-			}
-		} else {
-			/*dsc bitstream decoded at the dp last link*/
-			struct drm_dp_mst_port *immediate_upstream_port = NULL;
-			uint32_t end_link_bw = 0;
-
-			/*Get last DP link BW capability*/
-			if (dp_get_link_current_set_bw(&aconnector->mst_output_port->aux, &end_link_bw)) {
-				if (stream_kbps > end_link_bw) {
-					DRM_DEBUG_DRIVER("DSC decode at last link. Mode required bw can't fit into available bw\n");
-					return DC_FAIL_BANDWIDTH_VALIDATE;
-				}
-			}
-
-			/*Get virtual channel bandwidth between source and the link before the last link*/
-			if (aconnector->mst_output_port->parent->port_parent)
-				immediate_upstream_port = aconnector->mst_output_port->parent->port_parent;
+		}
 
-			if (immediate_upstream_port) {
-				virtual_channel_bw_in_kbps = kbps_from_pbn(immediate_upstream_port->full_pbn);
-				virtual_channel_bw_in_kbps = min(root_link_bw_in_kbps, virtual_channel_bw_in_kbps);
-				if (bw_range.min_kbps > virtual_channel_bw_in_kbps) {
-					DRM_DEBUG_DRIVER("DSC decode at last link. Max dsc compression can't fit into MST available bw\n");
-					return DC_FAIL_BANDWIDTH_VALIDATE;
-				}
+		if (end_to_end_bw_in_kbps < bw_range.stream_kbps) {
+			dc_dsc_get_default_config_option(stream->link->dc, &dsc_options);
+			dsc_options.max_target_bpp_limit_override_x16 = aconnector->base.display_info.max_dsc_bpp * 16;
+			if (dc_dsc_compute_config(stream->sink->ctx->dc->res_pool->dscs[0],
+					&stream->sink->dsc_caps.dsc_dec_caps,
+					&dsc_options,
+					end_to_end_bw_in_kbps,
+					&stream->timing,
+					dc_link_get_highest_encoding_format(stream->link),
+					&stream->timing.dsc_cfg)) {
+				stream->timing.flags.DSC = 1;
+				DRM_DEBUG_DRIVER("end-to-end bandwidth require dsc and dsc config found\n");
+			} else {
+				DRM_DEBUG_DRIVER("end-to-end bandwidth require dsc but dsc config not found\n");
+				return DC_FAIL_BANDWIDTH_VALIDATE;
 			}
 		}
-
-		/*Confirm if we can obtain dsc config*/
-		dc_dsc_get_default_config_option(stream->link->dc, &dsc_options);
-		dsc_options.max_target_bpp_limit_override_x16 = aconnector->base.display_info.max_dsc_bpp * 16;
-		if (dc_dsc_compute_config(stream->sink->ctx->dc->res_pool->dscs[0],
-				&stream->sink->dsc_caps.dsc_dec_caps,
-				&dsc_options,
-				end_to_end_bw_in_kbps,
-				&stream->timing,
-				dc_link_get_highest_encoding_format(stream->link),
-				&stream->timing.dsc_cfg)) {
-			stream->timing.flags.DSC = 1;
-			DRM_DEBUG_DRIVER("Require dsc and dsc config found\n");
-		} else {
-			DRM_DEBUG_DRIVER("Require dsc but can't find appropriate dsc config\n");
+	} else {
+		/* Check if mode could be supported within max slot
+		 * number of current mst link and full_pbn of mst links.
+		 */
+		int pbn_div, slot_num, max_slot_num;
+		enum dc_link_encoding_format link_encoding;
+		uint32_t stream_kbps =
+			dc_bandwidth_in_kbps_from_timing(&stream->timing,
+				dc_link_get_highest_encoding_format(stream->link));
+
+		pbn = kbps_to_peak_pbn(stream_kbps);
+		pbn_div = dm_mst_get_pbn_divider(stream->link);
+		slot_num = DIV_ROUND_UP(pbn, pbn_div);
+
+		link_encoding = dc_link_get_highest_encoding_format(stream->link);
+		if (link_encoding == DC_LINK_ENCODING_DP_8b_10b)
+			max_slot_num = 63;
+		else if (link_encoding == DC_LINK_ENCODING_DP_128b_132b)
+			max_slot_num = 64;
+		else {
+			DRM_DEBUG_DRIVER("Invalid link encoding format\n");
 			return DC_FAIL_BANDWIDTH_VALIDATE;
 		}
 
-		/* check is mst dsc output bandwidth branch_overall_throughput_0_mps */
-		switch (stream->timing.pixel_encoding) {
-		case PIXEL_ENCODING_RGB:
-		case PIXEL_ENCODING_YCBCR444:
-			branch_max_throughput_mps =
-				aconnector->dc_sink->dsc_caps.dsc_dec_caps.branch_overall_throughput_0_mps;
-			break;
-		case PIXEL_ENCODING_YCBCR422:
-		case PIXEL_ENCODING_YCBCR420:
-			branch_max_throughput_mps =
-				aconnector->dc_sink->dsc_caps.dsc_dec_caps.branch_overall_throughput_1_mps;
-			break;
-		default:
-			break;
+		if (slot_num > max_slot_num ||
+			pbn > aconnector->mst_output_port->full_pbn) {
+			DRM_DEBUG_DRIVER("Mode can not be supported within mst links!");
+			return DC_FAIL_BANDWIDTH_VALIDATE;
 		}
+	}
 
-		if (branch_max_throughput_mps != 0 &&
-			((stream->timing.pix_clk_100hz / 10) >  branch_max_throughput_mps * 1000)) {
-			DRM_DEBUG_DRIVER("DSC is required but max throughput mps fails");
-		return DC_FAIL_BANDWIDTH_VALIDATE;
-		}
-	} else {
-		DRM_DEBUG_DRIVER("DSC is required but can't find common dsc config.");
-		return DC_FAIL_BANDWIDTH_VALIDATE;
+	/* check is mst dsc output bandwidth branch_overall_throughput_0_mps */
+	switch (stream->timing.pixel_encoding) {
+	case PIXEL_ENCODING_RGB:
+	case PIXEL_ENCODING_YCBCR444:
+		branch_max_throughput_mps =
+			aconnector->dc_sink->dsc_caps.dsc_dec_caps.branch_overall_throughput_0_mps;
+		break;
+	case PIXEL_ENCODING_YCBCR422:
+	case PIXEL_ENCODING_YCBCR420:
+		branch_max_throughput_mps =
+			aconnector->dc_sink->dsc_caps.dsc_dec_caps.branch_overall_throughput_1_mps;
+		break;
+	default:
+		break;
 	}
-#endif
+
+	if (branch_max_throughput_mps != 0 &&
+		((stream->timing.pix_clk_100hz / 10) >  branch_max_throughput_mps * 1000))
+		return DC_FAIL_BANDWIDTH_VALIDATE;
+
 	return DC_OK;
 }