Merge tag 'amd-drm-next-5.6-2020-01-10-dp-mst-dsc' of git://people.freedesktop.org/~agd5f/linux into drm-next

amd-drm-next-5.6-2020-01-10-dp-mst-dsc:

drm:
- Add MST helper for PBN calculation of DSC modes
- Parse FEC caps on MST ports
- Add MST DPCD R/W functions
- Add MST helpers for virtual DPCD aux
- Add MST HUB quirk
- Add MST DSC enablement helpers

amdgpu:
- Enable MST DSC
- Add fair share algo for DSC bandwidth calcs
- Fix for 32 bit builds

Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Alex Deucher <alexdeucher@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200110214328.308549-1-alexander.deucher@amd.com

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

@@ -4933,12 +4933,13 @@ static int dm_encoder_helper_atomic_check(struct drm_encoder *encoder,
 								    is_y420);
 		bpp = convert_dc_color_depth_into_bpc(color_depth) * 3;
 		clock = adjusted_mode->clock;
-		dm_new_connector_state->pbn = drm_dp_calc_pbn_mode(clock, bpp);
+		dm_new_connector_state->pbn = drm_dp_calc_pbn_mode(clock, bpp, false);
 	}
 	dm_new_connector_state->vcpi_slots = drm_dp_atomic_find_vcpi_slots(state,
 									   mst_mgr,
 									   mst_port,
-									   dm_new_connector_state->pbn);
+									   dm_new_connector_state->pbn,
+									   0);
 	if (dm_new_connector_state->vcpi_slots < 0) {
 		DRM_DEBUG_ATOMIC("failed finding vcpi slots: %d\n", (int)dm_new_connector_state->vcpi_slots);
 		return dm_new_connector_state->vcpi_slots;
@@ -4951,6 +4952,71 @@ const struct drm_encoder_helper_funcs amdgpu_dm_encoder_helper_funcs = {
 	.atomic_check = dm_encoder_helper_atomic_check
 };
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+static int dm_update_mst_vcpi_slots_for_dsc(struct drm_atomic_state *state,
+					    struct dc_state *dc_state)
+{
+	struct dc_stream_state *stream = NULL;
+	struct drm_connector *connector;
+	struct drm_connector_state *new_con_state, *old_con_state;
+	struct amdgpu_dm_connector *aconnector;
+	struct dm_connector_state *dm_conn_state;
+	int i, j, clock, bpp;
+	int vcpi, pbn_div, pbn = 0;
+
+	for_each_oldnew_connector_in_state(state, connector, old_con_state, new_con_state, i) {
+
+		aconnector = to_amdgpu_dm_connector(connector);
+
+		if (!aconnector->port)
+			continue;
+
+		if (!new_con_state || !new_con_state->crtc)
+			continue;
+
+		dm_conn_state = to_dm_connector_state(new_con_state);
+
+		for (j = 0; j < dc_state->stream_count; j++) {
+			stream = dc_state->streams[j];
+			if (!stream)
+				continue;
+
+			if ((struct amdgpu_dm_connector*)stream->dm_stream_context == aconnector)
+				break;
+
+			stream = NULL;
+		}
+
+		if (!stream)
+			continue;
+
+		if (stream->timing.flags.DSC != 1) {
+			drm_dp_mst_atomic_enable_dsc(state,
+						     aconnector->port,
+						     dm_conn_state->pbn,
+						     0,
+						     false);
+			continue;
+		}
+
+		pbn_div = dm_mst_get_pbn_divider(stream->link);
+		bpp = stream->timing.dsc_cfg.bits_per_pixel;
+		clock = stream->timing.pix_clk_100hz / 10;
+		pbn = drm_dp_calc_pbn_mode(clock, bpp, true);
+		vcpi = drm_dp_mst_atomic_enable_dsc(state,
+						    aconnector->port,
+						    pbn, pbn_div,
+						    true);
+		if (vcpi < 0)
+			return vcpi;
+
+		dm_conn_state->pbn = pbn;
+		dm_conn_state->vcpi_slots = vcpi;
+	}
+	return 0;
+}
+#endif
+
 static void dm_drm_plane_reset(struct drm_plane *plane)
 {
 	struct dm_plane_state *amdgpu_state = NULL;
@@ -7829,6 +7895,29 @@ dm_determine_update_type_for_commit(struct amdgpu_display_manager *dm,
 	return ret;
 }
 
+static int add_affected_mst_dsc_crtcs(struct drm_atomic_state *state, struct drm_crtc *crtc)
+{
+	struct drm_connector *connector;
+	struct drm_connector_state *conn_state;
+	struct amdgpu_dm_connector *aconnector = NULL;
+	int i;
+	for_each_new_connector_in_state(state, connector, conn_state, i) {
+		if (conn_state->crtc != crtc)
+			continue;
+
+		aconnector = to_amdgpu_dm_connector(connector);
+		if (!aconnector->port || !aconnector->mst_port)
+			aconnector = NULL;
+		else
+			break;
+	}
+
+	if (!aconnector)
+		return 0;
+
+	return drm_dp_mst_add_affected_dsc_crtcs(state, &aconnector->mst_port->mst_mgr);
+}
+
 /**
  * amdgpu_dm_atomic_check() - Atomic check implementation for AMDgpu DM.
  * @dev: The DRM device
@@ -7881,6 +7970,16 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 	if (ret)
 		goto fail;
 
+	if (adev->asic_type >= CHIP_NAVI10) {
+		for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
+			if (drm_atomic_crtc_needs_modeset(new_crtc_state)) {
+				ret = add_affected_mst_dsc_crtcs(state, crtc);
+				if (ret)
+					goto fail;
+			}
+		}
+	}
+
 	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
 		if (!drm_atomic_crtc_needs_modeset(new_crtc_state) &&
 		    !new_crtc_state->color_mgmt_changed &&
@@ -7984,11 +8083,6 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 	if (ret)
 		goto fail;
 
-	/* Perform validation of MST topology in the state*/
-	ret = drm_dp_mst_atomic_check(state);
-	if (ret)
-		goto fail;
-
 	if (state->legacy_cursor_update) {
 		/*
 		 * This is a fast cursor update coming from the plane update
@@ -8057,6 +8151,15 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 		if (ret)
 			goto fail;
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+		if (!compute_mst_dsc_configs_for_state(state, dm_state->context))
+			goto fail;
+
+		ret = dm_update_mst_vcpi_slots_for_dsc(state, dm_state->context);
+		if (ret)
+			goto fail;
+#endif
+
 		if (dc_validate_global_state(dc, dm_state->context, false) != DC_OK) {
 			ret = -EINVAL;
 			goto fail;
@@ -8085,6 +8188,10 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 				dc_retain_state(old_dm_state->context);
 		}
 	}
+	/* Perform validation of MST topology in the state*/
+	ret = drm_dp_mst_atomic_check(state);
+	if (ret)
+		goto fail;
 
 	/* Store the overall update type for use later in atomic check. */
 	for_each_new_crtc_in_state (state, crtc, new_crtc_state, i) {

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

@@ -330,6 +330,7 @@ struct amdgpu_dm_connector {
 	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 */
 	struct amdgpu_i2c_adapter *i2c;

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

@@ -37,6 +37,7 @@
 #include "dc.h"
 #include "amdgpu_dm.h"
 #include "amdgpu_dm_irq.h"
+#include "amdgpu_dm_mst_types.h"
 
 #include "dm_helpers.h"
 
@@ -516,8 +517,24 @@ bool dm_helpers_dp_write_dsc_enable(
 )
 {
 	uint8_t enable_dsc = enable ? 1 : 0;
+	struct amdgpu_dm_connector *aconnector;
 
-	return dm_helpers_dp_write_dpcd(ctx, stream->sink->link, DP_DSC_ENABLE, &enable_dsc, 1);
+	if (!stream)
+		return false;
+
+	if (stream->signal == SIGNAL_TYPE_DISPLAY_PORT_MST) {
+		aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;
+
+		if (!aconnector->dsc_aux)
+			return false;
+
+		return (drm_dp_dpcd_write(aconnector->dsc_aux, DP_DSC_ENABLE, &enable_dsc, 1) >= 0);
+	}
+
+	if (stream->signal == SIGNAL_TYPE_DISPLAY_PORT)
+		return dm_helpers_dp_write_dpcd(ctx, stream->link, DP_DSC_ENABLE, &enable_dsc, 1);
+
+	return false;
 }
 
 bool dm_helpers_is_dp_sink_present(struct dc_link *link)

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

@@ -25,6 +25,7 @@
 
 #include <linux/version.h>
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_dp_mst_helper.h>
 #include "dm_services.h"
 #include "amdgpu.h"
 #include "amdgpu_dm.h"
@@ -39,6 +40,12 @@
 #if defined(CONFIG_DEBUG_FS)
 #include "amdgpu_dm_debugfs.h"
 #endif
+
+
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+#include "dc/dcn20/dcn20_resource.h"
+#endif
+
 /* #define TRACE_DPCD */
 
 #ifdef TRACE_DPCD
@@ -180,6 +187,30 @@ static const struct drm_connector_funcs dm_dp_mst_connector_funcs = {
 	.early_unregister = amdgpu_dm_mst_connector_early_unregister,
 };
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+static bool validate_dsc_caps_on_connector(struct amdgpu_dm_connector *aconnector)
+{
+	struct dc_sink *dc_sink = aconnector->dc_sink;
+	struct drm_dp_mst_port *port = aconnector->port;
+	u8 dsc_caps[16] = { 0 };
+
+	aconnector->dsc_aux = drm_dp_mst_dsc_aux_for_port(port);
+
+	if (!aconnector->dsc_aux)
+		return false;
+
+	if (drm_dp_dpcd_read(aconnector->dsc_aux, DP_DSC_SUPPORT, dsc_caps, 16) < 0)
+		return false;
+
+	if (!dc_dsc_parse_dsc_dpcd(aconnector->dc_link->ctx->dc,
+				   dsc_caps, NULL,
+				   &dc_sink->sink_dsc_caps.dsc_dec_caps))
+		return false;
+
+	return true;
+}
+#endif
+
 static int dm_dp_mst_get_modes(struct drm_connector *connector)
 {
 	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(connector);
@@ -222,10 +253,16 @@ static int dm_dp_mst_get_modes(struct drm_connector *connector)
 		/* dc_link_add_remote_sink returns a new reference */
 		aconnector->dc_sink = dc_sink;
 
-		if (aconnector->dc_sink)
+		if (aconnector->dc_sink) {
 			amdgpu_dm_update_freesync_caps(
 					connector, aconnector->edid);
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+			if (!validate_dsc_caps_on_connector(aconnector))
+				memset(&aconnector->dc_sink->sink_dsc_caps,
+				       0, sizeof(aconnector->dc_sink->sink_dsc_caps));
+#endif
+		}
 	}
 
 	drm_connector_update_edid_property(
@@ -466,3 +503,384 @@ void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm,
 		aconnector->connector_id);
 }
 
+int dm_mst_get_pbn_divider(struct dc_link *link)
+{
+	if (!link)
+		return 0;
+
+	return dc_link_bandwidth_kbps(link,
+			dc_link_get_link_cap(link)) / (8 * 1000 * 54);
+}
+
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+
+struct dsc_mst_fairness_params {
+	struct dc_crtc_timing *timing;
+	struct dc_sink *sink;
+	struct dc_dsc_bw_range bw_range;
+	bool compression_possible;
+	struct drm_dp_mst_port *port;
+};
+
+struct dsc_mst_fairness_vars {
+	int pbn;
+	bool dsc_enabled;
+	int bpp_x16;
+};
+
+static int kbps_to_peak_pbn(int kbps)
+{
+	u64 peak_kbps = kbps;
+
+	peak_kbps *= 1006;
+	peak_kbps = div_u64(peak_kbps, 1000);
+	return (int) DIV_ROUND_UP(peak_kbps * 64, (54 * 8 * 1000));
+}
+
+static void set_dsc_configs_from_fairness_vars(struct dsc_mst_fairness_params *params,
+		struct dsc_mst_fairness_vars *vars,
+		int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		memset(&params[i].timing->dsc_cfg, 0, sizeof(params[i].timing->dsc_cfg));
+		if (vars[i].dsc_enabled && dc_dsc_compute_config(
+					params[i].sink->ctx->dc->res_pool->dscs[0],
+					&params[i].sink->sink_dsc_caps.dsc_dec_caps,
+					params[i].sink->ctx->dc->debug.dsc_min_slice_height_override,
+					0,
+					params[i].timing,
+					&params[i].timing->dsc_cfg)) {
+			params[i].timing->flags.DSC = 1;
+			params[i].timing->dsc_cfg.bits_per_pixel = vars[i].bpp_x16;
+		} else {
+			params[i].timing->flags.DSC = 0;
+		}
+	}
+}
+
+static int bpp_x16_from_pbn(struct dsc_mst_fairness_params param, int pbn)
+{
+	struct dc_dsc_config dsc_config;
+	u64 kbps;
+
+	kbps = div_u64((u64)pbn * 994 * 8 * 54, 64);
+	dc_dsc_compute_config(
+			param.sink->ctx->dc->res_pool->dscs[0],
+			&param.sink->sink_dsc_caps.dsc_dec_caps,
+			param.sink->ctx->dc->debug.dsc_min_slice_height_override,
+			(int) kbps, param.timing, &dsc_config);
+
+	return dsc_config.bits_per_pixel;
+}
+
+static void increase_dsc_bpp(struct drm_atomic_state *state,
+			     struct dc_link *dc_link,
+			     struct dsc_mst_fairness_params *params,
+			     struct dsc_mst_fairness_vars *vars,
+			     int count)
+{
+	int i;
+	bool bpp_increased[MAX_PIPES];
+	int initial_slack[MAX_PIPES];
+	int min_initial_slack;
+	int next_index;
+	int remaining_to_increase = 0;
+	int pbn_per_timeslot;
+	int link_timeslots_used;
+	int fair_pbn_alloc;
+
+	for (i = 0; i < count; i++) {
+		if (vars[i].dsc_enabled) {
+			initial_slack[i] = kbps_to_peak_pbn(params[i].bw_range.max_kbps) - vars[i].pbn;
+			bpp_increased[i] = false;
+			remaining_to_increase += 1;
+		} else {
+			initial_slack[i] = 0;
+			bpp_increased[i] = true;
+		}
+	}
+
+	pbn_per_timeslot = dc_link_bandwidth_kbps(dc_link,
+			dc_link_get_link_cap(dc_link)) / (8 * 1000 * 54);
+
+	while (remaining_to_increase) {
+		next_index = -1;
+		min_initial_slack = -1;
+		for (i = 0; i < count; i++) {
+			if (!bpp_increased[i]) {
+				if (min_initial_slack == -1 || min_initial_slack > initial_slack[i]) {
+					min_initial_slack = initial_slack[i];
+					next_index = i;
+				}
+			}
+		}
+
+		if (next_index == -1)
+			break;
+
+		link_timeslots_used = 0;
+
+		for (i = 0; i < count; i++)
+			link_timeslots_used += DIV_ROUND_UP(vars[i].pbn, pbn_per_timeslot);
+
+		fair_pbn_alloc = (63 - link_timeslots_used) / remaining_to_increase * pbn_per_timeslot;
+
+		if (initial_slack[next_index] > fair_pbn_alloc) {
+			vars[next_index].pbn += fair_pbn_alloc;
+			if (drm_dp_atomic_find_vcpi_slots(state,
+							  params[next_index].port->mgr,
+							  params[next_index].port,
+							  vars[next_index].pbn,\
+							  dm_mst_get_pbn_divider(dc_link)) < 0)
+				return;
+			if (!drm_dp_mst_atomic_check(state)) {
+				vars[next_index].bpp_x16 = bpp_x16_from_pbn(params[next_index], vars[next_index].pbn);
+			} else {
+				vars[next_index].pbn -= fair_pbn_alloc;
+				if (drm_dp_atomic_find_vcpi_slots(state,
+								  params[next_index].port->mgr,
+								  params[next_index].port,
+								  vars[next_index].pbn,
+								  dm_mst_get_pbn_divider(dc_link)) < 0)
+					return;
+			}
+		} else {
+			vars[next_index].pbn += initial_slack[next_index];
+			if (drm_dp_atomic_find_vcpi_slots(state,
+							  params[next_index].port->mgr,
+							  params[next_index].port,
+							  vars[next_index].pbn,
+							  dm_mst_get_pbn_divider(dc_link)) < 0)
+				return;
+			if (!drm_dp_mst_atomic_check(state)) {
+				vars[next_index].bpp_x16 = params[next_index].bw_range.max_target_bpp_x16;
+			} else {
+				vars[next_index].pbn -= initial_slack[next_index];
+				if (drm_dp_atomic_find_vcpi_slots(state,
+								  params[next_index].port->mgr,
+								  params[next_index].port,
+								  vars[next_index].pbn,
+								  dm_mst_get_pbn_divider(dc_link)) < 0)
+					return;
+			}
+		}
+
+		bpp_increased[next_index] = true;
+		remaining_to_increase--;
+	}
+}
+
+static void try_disable_dsc(struct drm_atomic_state *state,
+			    struct dc_link *dc_link,
+			    struct dsc_mst_fairness_params *params,
+			    struct dsc_mst_fairness_vars *vars,
+			    int count)
+{
+	int i;
+	bool tried[MAX_PIPES];
+	int kbps_increase[MAX_PIPES];
+	int max_kbps_increase;
+	int next_index;
+	int remaining_to_try = 0;
+
+	for (i = 0; i < count; i++) {
+		if (vars[i].dsc_enabled && vars[i].bpp_x16 == params[i].bw_range.max_target_bpp_x16) {
+			kbps_increase[i] = params[i].bw_range.stream_kbps - params[i].bw_range.max_kbps;
+			tried[i] = false;
+			remaining_to_try += 1;
+		} else {
+			kbps_increase[i] = 0;
+			tried[i] = true;
+		}
+	}
+
+	while (remaining_to_try) {
+		next_index = -1;
+		max_kbps_increase = -1;
+		for (i = 0; i < count; i++) {
+			if (!tried[i]) {
+				if (max_kbps_increase == -1 || max_kbps_increase < kbps_increase[i]) {
+					max_kbps_increase = kbps_increase[i];
+					next_index = i;
+				}
+			}
+		}
+
+		if (next_index == -1)
+			break;
+
+		vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.stream_kbps);
+		if (drm_dp_atomic_find_vcpi_slots(state,
+						  params[next_index].port->mgr,
+						  params[next_index].port,
+						  vars[next_index].pbn,
+						  0) < 0)
+			return;
+
+		if (!drm_dp_mst_atomic_check(state)) {
+			vars[next_index].dsc_enabled = false;
+			vars[next_index].bpp_x16 = 0;
+		} else {
+			vars[next_index].pbn = kbps_to_peak_pbn(params[next_index].bw_range.max_kbps);
+			if (drm_dp_atomic_find_vcpi_slots(state,
+							  params[next_index].port->mgr,
+							  params[next_index].port,
+							  vars[next_index].pbn,
+							  dm_mst_get_pbn_divider(dc_link)) < 0)
+				return;
+		}
+
+		tried[next_index] = true;
+		remaining_to_try--;
+	}
+}
+
+static bool compute_mst_dsc_configs_for_link(struct drm_atomic_state *state,
+					     struct dc_state *dc_state,
+					     struct dc_link *dc_link)
+{
+	int i;
+	struct dc_stream_state *stream;
+	struct dsc_mst_fairness_params params[MAX_PIPES];
+	struct dsc_mst_fairness_vars vars[MAX_PIPES];
+	struct amdgpu_dm_connector *aconnector;
+	int count = 0;
+
+	memset(params, 0, sizeof(params));
+
+	/* Set up params */
+	for (i = 0; i < dc_state->stream_count; i++) {
+		struct dc_dsc_policy dsc_policy = {0};
+
+		stream = dc_state->streams[i];
+
+		if (stream->link != dc_link)
+			continue;
+
+		stream->timing.flags.DSC = 0;
+
+		params[count].timing = &stream->timing;
+		params[count].sink = stream->sink;
+		aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;
+		params[count].port = aconnector->port;
+		params[count].compression_possible = stream->sink->sink_dsc_caps.dsc_dec_caps.is_dsc_supported;
+		dc_dsc_get_policy_for_timing(params[count].timing, &dsc_policy);
+		if (!dc_dsc_compute_bandwidth_range(
+				stream->sink->ctx->dc->res_pool->dscs[0],
+				stream->sink->ctx->dc->debug.dsc_min_slice_height_override,
+				dsc_policy.min_target_bpp,
+				dsc_policy.max_target_bpp,
+				&stream->sink->sink_dsc_caps.dsc_dec_caps,
+				&stream->timing, &params[count].bw_range))
+			params[count].bw_range.stream_kbps = dc_bandwidth_in_kbps_from_timing(&stream->timing);
+
+		count++;
+	}
+	/* Try no compression */
+	for (i = 0; i < count; i++) {
+		vars[i].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps);
+		vars[i].dsc_enabled = false;
+		vars[i].bpp_x16 = 0;
+		if (drm_dp_atomic_find_vcpi_slots(state,
+						 params[i].port->mgr,
+						 params[i].port,
+						 vars[i].pbn,
+						 0) < 0)
+			return false;
+	}
+	if (!drm_dp_mst_atomic_check(state)) {
+		set_dsc_configs_from_fairness_vars(params, vars, count);
+		return true;
+	}
+
+	/* Try max compression */
+	for (i = 0; i < count; i++) {
+		if (params[i].compression_possible) {
+			vars[i].pbn = kbps_to_peak_pbn(params[i].bw_range.min_kbps);
+			vars[i].dsc_enabled = true;
+			vars[i].bpp_x16 = params[i].bw_range.min_target_bpp_x16;
+			if (drm_dp_atomic_find_vcpi_slots(state,
+							  params[i].port->mgr,
+							  params[i].port,
+							  vars[i].pbn,
+							  dm_mst_get_pbn_divider(dc_link)) < 0)
+				return false;
+		} else {
+			vars[i].pbn = kbps_to_peak_pbn(params[i].bw_range.stream_kbps);
+			vars[i].dsc_enabled = false;
+			vars[i].bpp_x16 = 0;
+			if (drm_dp_atomic_find_vcpi_slots(state,
+							  params[i].port->mgr,
+							  params[i].port,
+							  vars[i].pbn,
+							  0) < 0)
+				return false;
+		}
+	}
+	if (drm_dp_mst_atomic_check(state))
+		return false;
+
+	/* Optimize degree of compression */
+	increase_dsc_bpp(state, dc_link, params, vars, count);
+
+	try_disable_dsc(state, dc_link, params, vars, count);
+
+	set_dsc_configs_from_fairness_vars(params, vars, count);
+
+	return true;
+}
+
+bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
+				       struct dc_state *dc_state)
+{
+	int i, j;
+	struct dc_stream_state *stream;
+	bool computed_streams[MAX_PIPES];
+	struct amdgpu_dm_connector *aconnector;
+
+	for (i = 0; i < dc_state->stream_count; i++)
+		computed_streams[i] = false;
+
+	for (i = 0; i < dc_state->stream_count; i++) {
+		stream = dc_state->streams[i];
+
+		if (stream->signal != SIGNAL_TYPE_DISPLAY_PORT_MST)
+			continue;
+
+		aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;
+
+		if (!aconnector || !aconnector->dc_sink)
+			continue;
+
+		if (!aconnector->dc_sink->sink_dsc_caps.dsc_dec_caps.is_dsc_supported)
+			continue;
+
+		if (computed_streams[i])
+			continue;
+
+		mutex_lock(&aconnector->mst_mgr.lock);
+		if (!compute_mst_dsc_configs_for_link(state, dc_state, stream->link)) {
+			mutex_unlock(&aconnector->mst_mgr.lock);
+			return false;
+		}
+		mutex_unlock(&aconnector->mst_mgr.lock);
+
+		for (j = 0; j < dc_state->stream_count; j++) {
+			if (dc_state->streams[j]->link == stream->link)
+				computed_streams[j] = true;
+		}
+	}
+
+	for (i = 0; i < dc_state->stream_count; i++) {
+		stream = dc_state->streams[i];
+
+		if (stream->timing.flags.DSC == 1)
+			dcn20_add_dsc_to_stream_resource(stream->ctx->dc, dc_state, stream);
+	}
+
+	return true;
+}
+
+#endif

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

@@ -29,7 +29,14 @@
 struct amdgpu_display_manager;
 struct amdgpu_dm_connector;
 
+int dm_mst_get_pbn_divider(struct dc_link *link);
+
 void amdgpu_dm_initialize_dp_connector(struct amdgpu_display_manager *dm,
 				       struct amdgpu_dm_connector *aconnector);
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
+				       struct dc_state *dc_state);
+#endif
+
 #endif

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

@@ -525,6 +525,9 @@ bool dp_set_dsc_pps_sdp(struct pipe_ctx *pipe_ctx, bool enable)
 		struct dsc_config dsc_cfg;
 		uint8_t dsc_packed_pps[128];
 
+		memset(&dsc_cfg, 0, sizeof(dsc_cfg));
+		memset(dsc_packed_pps, 0, 128);
+
 		/* Enable DSC hw block */
 		dsc_cfg.pic_width = stream->timing.h_addressable + stream->timing.h_border_left + stream->timing.h_border_right;
 		dsc_cfg.pic_height = stream->timing.v_addressable + stream->timing.v_border_top + stream->timing.v_border_bottom;

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dsc.c

@@ -206,6 +206,9 @@ static bool dsc2_get_packed_pps(struct display_stream_compressor *dsc, const str
 	struct dsc_reg_values dsc_reg_vals;
 	struct dsc_optc_config dsc_optc_cfg;
 
+	memset(&dsc_reg_vals, 0, sizeof(dsc_reg_vals));
+	memset(&dsc_optc_cfg, 0, sizeof(dsc_optc_cfg));
+
 	DC_LOG_DSC("Getting packed DSC PPS for DSC Config:");
 	dsc_config_log(dsc, dsc_cfg);
 	DC_LOG_DSC("DSC Picture Parameter Set (PPS):");

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c

@@ -1569,7 +1569,7 @@ static void release_dsc(struct resource_context *res_ctx,
 
 
 
-static enum dc_status add_dsc_to_stream_resource(struct dc *dc,
+enum dc_status dcn20_add_dsc_to_stream_resource(struct dc *dc,
 		struct dc_state *dc_ctx,
 		struct dc_stream_state *dc_stream)
 {
@@ -1584,6 +1584,9 @@ static enum dc_status add_dsc_to_stream_resource(struct dc *dc,
 		if (pipe_ctx->stream != dc_stream)
 			continue;
 
+		if (pipe_ctx->stream_res.dsc)
+			continue;
+
 		acquire_dsc(&dc_ctx->res_ctx, pool, &pipe_ctx->stream_res.dsc, i);
 
 		/* The number of DSCs can be less than the number of pipes */
@@ -1632,7 +1635,7 @@ enum dc_status dcn20_add_stream_to_ctx(struct dc *dc, struct dc_state *new_ctx,
 
 	/* Get a DSC if required and available */
 	if (result == DC_OK && dc_stream->timing.flags.DSC)
-		result = add_dsc_to_stream_resource(dc, new_ctx, dc_stream);
+		result = dcn20_add_dsc_to_stream_resource(dc, new_ctx, dc_stream);
 
 	if (result == DC_OK)
 		result = dcn20_build_mapped_resource(dc, new_ctx, dc_stream);

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.h

@@ -157,6 +157,7 @@ void dcn20_calculate_dlg_params(
 
 enum dc_status dcn20_build_mapped_resource(const struct dc *dc, struct dc_state *context, struct dc_stream_state *stream);
 enum dc_status dcn20_add_stream_to_ctx(struct dc *dc, struct dc_state *new_ctx, struct dc_stream_state *dc_stream);
+enum dc_status dcn20_add_dsc_to_stream_resource(struct dc *dc, struct dc_state *dc_ctx, struct dc_stream_state *dc_stream);
 enum dc_status dcn20_remove_stream_from_ctx(struct dc *dc, struct dc_state *new_ctx, struct dc_stream_state *dc_stream);
 enum dc_status dcn20_get_default_swizzle_mode(struct dc_plane_state *plane_state);
 

drivers/gpu/drm/drm_dp_aux_dev.c

@@ -163,11 +163,7 @@ static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 			break;
 		}
 
-		if (aux_dev->aux->is_remote)
+		res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
-			res = drm_dp_mst_dpcd_read(aux_dev->aux, pos, buf,
-						   todo);
-		else
-			res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
 
 		if (res <= 0)
 			break;
@@ -215,11 +211,7 @@ static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 			break;
 		}
 
-		if (aux_dev->aux->is_remote)
+		res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
-			res = drm_dp_mst_dpcd_write(aux_dev->aux, pos, buf,
-						    todo);
-		else
-			res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
 
 		if (res <= 0)
 			break;

drivers/gpu/drm/drm_dp_helper.c

@@ -32,6 +32,7 @@
 #include <drm/drm_dp_helper.h>
 #include <drm/drm_print.h>
 #include <drm/drm_vblank.h>
+#include <drm/drm_dp_mst_helper.h>
 
 #include "drm_crtc_helper_internal.h"
 
@@ -266,7 +267,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 
 /**
  * drm_dp_dpcd_read() - read a series of bytes from the DPCD
- * @aux: DisplayPort AUX channel
+ * @aux: DisplayPort AUX channel (SST or MST)
  * @offset: address of the (first) register to read
  * @buffer: buffer to store the register values
  * @size: number of bytes in @buffer
@@ -295,13 +296,18 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 	 * We just have to do it before any DPCD access and hope that the
 	 * monitor doesn't power down exactly after the throw away read.
 	 */
-	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV, buffer,
+	if (!aux->is_remote) {
-				 1);
+		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, DP_DPCD_REV,
-	if (ret != 1)
+					 buffer, 1);
-		goto out;
+		if (ret != 1)
+			goto out;
+	}
 
-	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer,
+	if (aux->is_remote)
-				 size);
+		ret = drm_dp_mst_dpcd_read(aux, offset, buffer, size);
+	else
+		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset,
+					 buffer, size);
 
 out:
 	drm_dp_dump_access(aux, DP_AUX_NATIVE_READ, offset, buffer, ret);
@@ -311,7 +317,7 @@ EXPORT_SYMBOL(drm_dp_dpcd_read);
 
 /**
  * drm_dp_dpcd_write() - write a series of bytes to the DPCD
- * @aux: DisplayPort AUX channel
+ * @aux: DisplayPort AUX channel (SST or MST)
  * @offset: address of the (first) register to write
  * @buffer: buffer containing the values to write
  * @size: number of bytes in @buffer
@@ -328,8 +334,12 @@ ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
 {
 	int ret;
 
-	ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer,
+	if (aux->is_remote)
-				 size);
+		ret = drm_dp_mst_dpcd_write(aux, offset, buffer, size);
+	else
+		ret = drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset,
+					 buffer, size);
+
 	drm_dp_dump_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer, ret);
 	return ret;
 }
@@ -968,6 +978,19 @@ static void drm_dp_aux_crc_work(struct work_struct *work)
 	}
 }
 
+/**
+ * drm_dp_remote_aux_init() - minimally initialise a remote aux channel
+ * @aux: DisplayPort AUX channel
+ *
+ * Used for remote aux channel in general. Merely initialize the crc work
+ * struct.
+ */
+void drm_dp_remote_aux_init(struct drm_dp_aux *aux)
+{
+	INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work);
+}
+EXPORT_SYMBOL(drm_dp_remote_aux_init);
+
 /**
  * drm_dp_aux_init() - minimally initialise an aux channel
  * @aux: DisplayPort AUX channel
@@ -1155,6 +1178,8 @@ static const struct dpcd_quirk dpcd_quirk_list[] = {
 	{ OUI(0x00, 0x10, 0xfa), DEVICE_ID_ANY, false, BIT(DP_DPCD_QUIRK_NO_PSR) },
 	/* CH7511 seems to leave SINK_COUNT zeroed */
 	{ OUI(0x00, 0x00, 0x00), DEVICE_ID('C', 'H', '7', '5', '1', '1'), false, BIT(DP_DPCD_QUIRK_NO_SINK_COUNT) },
+	/* Synaptics DP1.4 MST hubs can support DSC without virtual DPCD */
+	{ OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) },
 };
 
 #undef OUI

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -853,6 +853,7 @@ static bool drm_dp_sideband_parse_enum_path_resources_ack(struct drm_dp_sideband
 {
 	int idx = 1;
 	repmsg->u.path_resources.port_number = (raw->msg[idx] >> 4) & 0xf;
+	repmsg->u.path_resources.fec_capable = raw->msg[idx] & 0x1;
 	idx++;
 	if (idx > raw->curlen)
 		goto fail_len;
@@ -2174,6 +2175,7 @@ drm_dp_mst_topology_unlink_port(struct drm_dp_mst_topology_mgr *mgr,
 				struct drm_dp_mst_port *port)
 {
 	mutex_lock(&mgr->lock);
+	port->parent->num_ports--;
 	list_del(&port->next);
 	mutex_unlock(&mgr->lock);
 	drm_dp_mst_topology_put_port(port);
@@ -2198,6 +2200,9 @@ drm_dp_mst_add_port(struct drm_device *dev,
 	port->aux.dev = dev->dev;
 	port->aux.is_remote = true;
 
+	/* initialize the MST downstream port's AUX crc work queue */
+	drm_dp_remote_aux_init(&port->aux);
+
 	/*
 	 * Make sure the memory allocation for our parent branch stays
 	 * around until our own memory allocation is released
@@ -2273,6 +2278,7 @@ drm_dp_mst_handle_link_address_port(struct drm_dp_mst_branch *mstb,
 		mutex_lock(&mgr->lock);
 		drm_dp_mst_topology_get_port(port);
 		list_add(&port->next, &mstb->ports);
+		mstb->num_ports++;
 		mutex_unlock(&mgr->lock);
 	}
 
@@ -2951,6 +2957,7 @@ drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
 				      path_res->avail_payload_bw_number);
 			port->available_pbn =
 				path_res->avail_payload_bw_number;
+			port->fec_capable = path_res->fec_capable;
 		}
 	}
 
@@ -4089,6 +4096,7 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
  * @mgr: MST topology manager for the port
  * @port: port to find vcpi slots for
  * @pbn: bandwidth required for the mode in PBN
+ * @pbn_div: divider for DSC mode that takes FEC into account
  *
  * Allocates VCPI slots to @port, replacing any previous VCPI allocations it
  * may have had. Any atomic drivers which support MST must call this function
@@ -4115,11 +4123,12 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
  */
 int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 				  struct drm_dp_mst_topology_mgr *mgr,
-				  struct drm_dp_mst_port *port, int pbn)
+				  struct drm_dp_mst_port *port, int pbn,
+				  int pbn_div)
 {
 	struct drm_dp_mst_topology_state *topology_state;
 	struct drm_dp_vcpi_allocation *pos, *vcpi = NULL;
-	int prev_slots, req_slots;
+	int prev_slots, prev_bw, req_slots;
 
 	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
 	if (IS_ERR(topology_state))
@@ -4130,6 +4139,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 		if (pos->port == port) {
 			vcpi = pos;
 			prev_slots = vcpi->vcpi;
+			prev_bw = vcpi->pbn;
 
 			/*
 			 * This should never happen, unless the driver tries
@@ -4145,14 +4155,22 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 			break;
 		}
 	}
-	if (!vcpi)
+	if (!vcpi) {
 		prev_slots = 0;
+		prev_bw = 0;
+	}
 
-	req_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
+	if (pbn_div <= 0)
+		pbn_div = mgr->pbn_div;
+
+	req_slots = DIV_ROUND_UP(pbn, pbn_div);
 
 	DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] VCPI %d -> %d\n",
 			 port->connector->base.id, port->connector->name,
 			 port, prev_slots, req_slots);
+	DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] PBN %d -> %d\n",
+			 port->connector->base.id, port->connector->name,
+			 port, prev_bw, pbn);
 
 	/* Add the new allocation to the state */
 	if (!vcpi) {
@@ -4165,6 +4183,7 @@ int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 		list_add(&vcpi->next, &topology_state->vcpis);
 	}
 	vcpi->vcpi = req_slots;
+	vcpi->pbn = pbn;
 
 	return req_slots;
 }
@@ -4415,10 +4434,11 @@ EXPORT_SYMBOL(drm_dp_check_act_status);
  * drm_dp_calc_pbn_mode() - Calculate the PBN for a mode.
  * @clock: dot clock for the mode
  * @bpp: bpp for the mode.
+ * @dsc: DSC mode. If true, bpp has units of 1/16 of a bit per pixel
  *
  * This uses the formula in the spec to calculate the PBN value for a mode.
  */
-int drm_dp_calc_pbn_mode(int clock, int bpp)
+int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc)
 {
 	/*
 	 * margin 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006
@@ -4429,7 +4449,16 @@ int drm_dp_calc_pbn_mode(int clock, int bpp)
 	 * peak_kbps *= (1006/1000)
 	 * peak_kbps *= (64/54)
 	 * peak_kbps *= 8    convert to bytes
+	 *
+	 * If the bpp is in units of 1/16, further divide by 16. Put this
+	 * factor in the numerator rather than the denominator to avoid
+	 * integer overflow
 	 */
+
+	if (dsc)
+		return DIV_ROUND_UP_ULL(mul_u32_u32(clock * (bpp / 16), 64 * 1006),
+					8 * 54 * 1000 * 1000);
+
 	return DIV_ROUND_UP_ULL(mul_u32_u32(clock * bpp, 64 * 1006),
 				8 * 54 * 1000 * 1000);
 }
@@ -4731,9 +4760,61 @@ static void drm_dp_mst_destroy_state(struct drm_private_obj *obj,
 	kfree(mst_state);
 }
 
+static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
+						 struct drm_dp_mst_branch *branch)
+{
+	while (port->parent) {
+		if (port->parent == branch)
+			return true;
+
+		if (port->parent->port_parent)
+			port = port->parent->port_parent;
+		else
+			break;
+	}
+	return false;
+}
+
+static inline
+int drm_dp_mst_atomic_check_bw_limit(struct drm_dp_mst_branch *branch,
+				     struct drm_dp_mst_topology_state *mst_state)
+{
+	struct drm_dp_mst_port *port;
+	struct drm_dp_vcpi_allocation *vcpi;
+	int pbn_limit = 0, pbn_used = 0;
+
+	list_for_each_entry(port, &branch->ports, next) {
+		if (port->mstb)
+			if (drm_dp_mst_atomic_check_bw_limit(port->mstb, mst_state))
+				return -ENOSPC;
+
+		if (port->available_pbn > 0)
+			pbn_limit = port->available_pbn;
+	}
+	DRM_DEBUG_ATOMIC("[MST BRANCH:%p] branch has %d PBN available\n",
+			 branch, pbn_limit);
+
+	list_for_each_entry(vcpi, &mst_state->vcpis, next) {
+		if (!vcpi->pbn)
+			continue;
+
+		if (drm_dp_mst_port_downstream_of_branch(vcpi->port, branch))
+			pbn_used += vcpi->pbn;
+	}
+	DRM_DEBUG_ATOMIC("[MST BRANCH:%p] branch used %d PBN\n",
+			 branch, pbn_used);
+
+	if (pbn_used > pbn_limit) {
+		DRM_DEBUG_ATOMIC("[MST BRANCH:%p] No available bandwidth\n",
+				 branch);
+		return -ENOSPC;
+	}
+	return 0;
+}
+
 static inline int
-drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr,
+drm_dp_mst_atomic_check_vcpi_alloc_limit(struct drm_dp_mst_topology_mgr *mgr,
-				       struct drm_dp_mst_topology_state *mst_state)
+					 struct drm_dp_mst_topology_state *mst_state)
 {
 	struct drm_dp_vcpi_allocation *vcpi;
 	int avail_slots = 63, payload_count = 0;
@@ -4770,6 +4851,128 @@ drm_dp_mst_atomic_check_topology_state(struct drm_dp_mst_topology_mgr *mgr,
 	return 0;
 }
 
+/**
+ * drm_dp_mst_add_affected_dsc_crtcs
+ * @state: Pointer to the new struct drm_dp_mst_topology_state
+ * @mgr: MST topology manager
+ *
+ * Whenever there is a change in mst topology
+ * DSC configuration would have to be recalculated
+ * therefore we need to trigger modeset on all affected
+ * CRTCs in that topology
+ *
+ * See also:
+ * drm_dp_mst_atomic_enable_dsc()
+ */
+int drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state, struct drm_dp_mst_topology_mgr *mgr)
+{
+	struct drm_dp_mst_topology_state *mst_state;
+	struct drm_dp_vcpi_allocation *pos;
+	struct drm_connector *connector;
+	struct drm_connector_state *conn_state;
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *crtc_state;
+
+	mst_state = drm_atomic_get_mst_topology_state(state, mgr);
+
+	if (IS_ERR(mst_state))
+		return -EINVAL;
+
+	list_for_each_entry(pos, &mst_state->vcpis, next) {
+
+		connector = pos->port->connector;
+
+		if (!connector)
+			return -EINVAL;
+
+		conn_state = drm_atomic_get_connector_state(state, connector);
+
+		if (IS_ERR(conn_state))
+			return PTR_ERR(conn_state);
+
+		crtc = conn_state->crtc;
+
+		if (WARN_ON(!crtc))
+			return -EINVAL;
+
+		if (!drm_dp_mst_dsc_aux_for_port(pos->port))
+			continue;
+
+		crtc_state = drm_atomic_get_crtc_state(mst_state->base.state, crtc);
+
+		if (IS_ERR(crtc_state))
+			return PTR_ERR(crtc_state);
+
+		DRM_DEBUG_ATOMIC("[MST MGR:%p] Setting mode_changed flag on CRTC %p\n",
+				 mgr, crtc);
+
+		crtc_state->mode_changed = true;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_mst_add_affected_dsc_crtcs);
+
+/**
+ * drm_dp_mst_atomic_enable_dsc - Set DSC Enable Flag to On/Off
+ * @state: Pointer to the new drm_atomic_state
+ * @port: Pointer to the affected MST Port
+ * @pbn: Newly recalculated bw required for link with DSC enabled
+ * @pbn_div: Divider to calculate correct number of pbn per slot
+ * @enable: Boolean flag to enable or disable DSC on the port
+ *
+ * This function enables DSC on the given Port
+ * by recalculating its vcpi from pbn provided
+ * and sets dsc_enable flag to keep track of which
+ * ports have DSC enabled
+ *
+ */
+int drm_dp_mst_atomic_enable_dsc(struct drm_atomic_state *state,
+				 struct drm_dp_mst_port *port,
+				 int pbn, int pbn_div,
+				 bool enable)
+{
+	struct drm_dp_mst_topology_state *mst_state;
+	struct drm_dp_vcpi_allocation *pos;
+	bool found = false;
+	int vcpi = 0;
+
+	mst_state = drm_atomic_get_mst_topology_state(state, port->mgr);
+
+	if (IS_ERR(mst_state))
+		return PTR_ERR(mst_state);
+
+	list_for_each_entry(pos, &mst_state->vcpis, next) {
+		if (pos->port == port) {
+			found = true;
+			break;
+		}
+	}
+
+	if (!found) {
+		DRM_DEBUG_ATOMIC("[MST PORT:%p] Couldn't find VCPI allocation in mst state %p\n",
+				 port, mst_state);
+		return -EINVAL;
+	}
+
+	if (pos->dsc_enabled == enable) {
+		DRM_DEBUG_ATOMIC("[MST PORT:%p] DSC flag is already set to %d, returning %d VCPI slots\n",
+				 port, enable, pos->vcpi);
+		vcpi = pos->vcpi;
+	}
+
+	if (enable) {
+		vcpi = drm_dp_atomic_find_vcpi_slots(state, port->mgr, port, pbn, pbn_div);
+		DRM_DEBUG_ATOMIC("[MST PORT:%p] Enabling DSC flag, reallocating %d VCPI slots on the port\n",
+				 port, vcpi);
+		if (vcpi < 0)
+			return -EINVAL;
+	}
+
+	pos->dsc_enabled = enable;
+
+	return vcpi;
+}
+EXPORT_SYMBOL(drm_dp_mst_atomic_enable_dsc);
 /**
  * drm_dp_mst_atomic_check - Check that the new state of an MST topology in an
  * atomic update is valid
@@ -4798,7 +5001,10 @@ int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
 	int i, ret = 0;
 
 	for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {
-		ret = drm_dp_mst_atomic_check_topology_state(mgr, mst_state);
+		ret = drm_dp_mst_atomic_check_vcpi_alloc_limit(mgr, mst_state);
+		if (ret)
+			break;
+		ret = drm_dp_mst_atomic_check_bw_limit(mgr->mst_primary, mst_state);
 		if (ret)
 			break;
 	}
@@ -5062,3 +5268,173 @@ static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_aux *aux)
 {
 	i2c_del_adapter(&aux->ddc);
 }
+
+/**
+ * drm_dp_mst_is_virtual_dpcd() - Is the given port a virtual DP Peer Device
+ * @port: The port to check
+ *
+ * A single physical MST hub object can be represented in the topology
+ * by multiple branches, with virtual ports between those branches.
+ *
+ * As of DP1.4, An MST hub with internal (virtual) ports must expose
+ * certain DPCD registers over those ports. See sections 2.6.1.1.1
+ * and 2.6.1.1.2 of Display Port specification v1.4 for details.
+ *
+ * May acquire mgr->lock
+ *
+ * Returns:
+ * true if the port is a virtual DP peer device, false otherwise
+ */
+static bool drm_dp_mst_is_virtual_dpcd(struct drm_dp_mst_port *port)
+{
+	struct drm_dp_mst_port *downstream_port;
+
+	if (!port || port->dpcd_rev < DP_DPCD_REV_14)
+		return false;
+
+	/* Virtual DP Sink (Internal Display Panel) */
+	if (port->port_num >= 8)
+		return true;
+
+	/* DP-to-HDMI Protocol Converter */
+	if (port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV &&
+	    !port->mcs &&
+	    port->ldps)
+		return true;
+
+	/* DP-to-DP */
+	mutex_lock(&port->mgr->lock);
+	if (port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
+	    port->mstb &&
+	    port->mstb->num_ports == 2) {
+		list_for_each_entry(downstream_port, &port->mstb->ports, next) {
+			if (downstream_port->pdt == DP_PEER_DEVICE_SST_SINK &&
+			    !downstream_port->input) {
+				mutex_unlock(&port->mgr->lock);
+				return true;
+			}
+		}
+	}
+	mutex_unlock(&port->mgr->lock);
+
+	return false;
+}
+
+/**
+ * drm_dp_mst_dsc_aux_for_port() - Find the correct aux for DSC
+ * @port: The port to check. A leaf of the MST tree with an attached display.
+ *
+ * Depending on the situation, DSC may be enabled via the endpoint aux,
+ * the immediately upstream aux, or the connector's physical aux.
+ *
+ * This is both the correct aux to read DSC_CAPABILITY and the
+ * correct aux to write DSC_ENABLED.
+ *
+ * This operation can be expensive (up to four aux reads), so
+ * the caller should cache the return.
+ *
+ * Returns:
+ * NULL if DSC cannot be enabled on this port, otherwise the aux device
+ */
+struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port)
+{
+	struct drm_dp_mst_port *immediate_upstream_port;
+	struct drm_dp_mst_port *fec_port;
+	struct drm_dp_desc desc = { 0 };
+	u8 endpoint_fec;
+	u8 endpoint_dsc;
+
+	if (!port)
+		return NULL;
+
+	if (port->parent->port_parent)
+		immediate_upstream_port = port->parent->port_parent;
+	else
+		immediate_upstream_port = NULL;
+
+	fec_port = immediate_upstream_port;
+	while (fec_port) {
+		/*
+		 * Each physical link (i.e. not a virtual port) between the
+		 * output and the primary device must support FEC
+		 */
+		if (!drm_dp_mst_is_virtual_dpcd(fec_port) &&
+		    !fec_port->fec_capable)
+			return NULL;
+
+		fec_port = fec_port->parent->port_parent;
+	}
+
+	/* DP-to-DP peer device */
+	if (drm_dp_mst_is_virtual_dpcd(immediate_upstream_port)) {
+		u8 upstream_dsc;
+
+		if (drm_dp_dpcd_read(&port->aux,
+				     DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
+			return NULL;
+		if (drm_dp_dpcd_read(&port->aux,
+				     DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
+			return NULL;
+		if (drm_dp_dpcd_read(&immediate_upstream_port->aux,
+				     DP_DSC_SUPPORT, &upstream_dsc, 1) != 1)
+			return NULL;
+
+		/* Enpoint decompression with DP-to-DP peer device */
+		if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
+		    (endpoint_fec & DP_FEC_CAPABLE) &&
+		    (upstream_dsc & 0x2) /* DSC passthrough */)
+			return &port->aux;
+
+		/* Virtual DPCD decompression with DP-to-DP peer device */
+		return &immediate_upstream_port->aux;
+	}
+
+	/* Virtual DPCD decompression with DP-to-HDMI or Virtual DP Sink */
+	if (drm_dp_mst_is_virtual_dpcd(port))
+		return &port->aux;
+
+	/*
+	 * Synaptics quirk
+	 * Applies to ports for which:
+	 * - Physical aux has Synaptics OUI
+	 * - DPv1.4 or higher
+	 * - Port is on primary branch device
+	 * - Not a VGA adapter (DP_DWN_STRM_PORT_TYPE_ANALOG)
+	 */
+	if (drm_dp_read_desc(port->mgr->aux, &desc, true))
+		return NULL;
+
+	if (drm_dp_has_quirk(&desc, DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) &&
+	    port->mgr->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14 &&
+	    port->parent == port->mgr->mst_primary) {
+		u8 downstreamport;
+
+		if (drm_dp_dpcd_read(&port->aux, DP_DOWNSTREAMPORT_PRESENT,
+				     &downstreamport, 1) < 0)
+			return NULL;
+
+		if ((downstreamport & DP_DWN_STRM_PORT_PRESENT) &&
+		   ((downstreamport & DP_DWN_STRM_PORT_TYPE_MASK)
+		     != DP_DWN_STRM_PORT_TYPE_ANALOG))
+			return port->mgr->aux;
+	}
+
+	/*
+	 * The check below verifies if the MST sink
+	 * connected to the GPU is capable of DSC -
+	 * therefore the endpoint needs to be
+	 * both DSC and FEC capable.
+	 */
+	if (drm_dp_dpcd_read(&port->aux,
+	   DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
+		return NULL;
+	if (drm_dp_dpcd_read(&port->aux,
+	   DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
+		return NULL;
+	if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
+	   (endpoint_fec & DP_FEC_CAPABLE))
+		return &port->aux;
+
+	return NULL;
+}
+EXPORT_SYMBOL(drm_dp_mst_dsc_aux_for_port);

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

@@ -61,10 +61,11 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
 		crtc_state->pipe_bpp = bpp;
 
 		crtc_state->pbn = drm_dp_calc_pbn_mode(adjusted_mode->crtc_clock,
-						       crtc_state->pipe_bpp);
+						       crtc_state->pipe_bpp,
+						       false);
 
 		slots = drm_dp_atomic_find_vcpi_slots(state, &intel_dp->mst_mgr,
-						      port, crtc_state->pbn);
+						      port, crtc_state->pbn, 0);
 		if (slots == -EDEADLK)
 			return slots;
 		if (slots >= 0)

drivers/gpu/drm/nouveau/dispnv50/disp.c

@@ -806,11 +806,11 @@ nv50_msto_atomic_check(struct drm_encoder *encoder,
 		 * topology
 		 */
 		asyh->or.bpc = min(connector->display_info.bpc, 8U);
-		asyh->dp.pbn = drm_dp_calc_pbn_mode(clock, asyh->or.bpc * 3);
+		asyh->dp.pbn = drm_dp_calc_pbn_mode(clock, asyh->or.bpc * 3, false);
 	}
 
 	slots = drm_dp_atomic_find_vcpi_slots(state, &mstm->mgr, mstc->port,
-					      asyh->dp.pbn);
+					      asyh->dp.pbn, 0);
 	if (slots < 0)
 		return slots;
 

drivers/gpu/drm/radeon/radeon_dp_mst.c

@@ -518,7 +518,7 @@ static bool radeon_mst_mode_fixup(struct drm_encoder *encoder,
 
 	mst_enc = radeon_encoder->enc_priv;
 
-	mst_enc->pbn = drm_dp_calc_pbn_mode(adjusted_mode->clock, bpp);
+	mst_enc->pbn = drm_dp_calc_pbn_mode(adjusted_mode->clock, bpp, false);
 
 	mst_enc->primary->active_device = mst_enc->primary->devices & mst_enc->connector->devices;
 	DRM_DEBUG_KMS("setting active device to %08x from %08x %08x for encoder %d\n",

drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c

@@ -18,15 +18,19 @@ int igt_dp_mst_calc_pbn_mode(void *ignored)
 		int rate;
 		int bpp;
 		int expected;
+		bool dsc;
 	} test_params[] = {
-		{ 154000, 30, 689 },
+		{ 154000, 30, 689, false },
-		{ 234000, 30, 1047 },
+		{ 234000, 30, 1047, false },
-		{ 297000, 24, 1063 },
+		{ 297000, 24, 1063, false },
+		{ 332880, 24, 50, true },
+		{ 324540, 24, 49, true },
 	};
 
 	for (i = 0; i < ARRAY_SIZE(test_params); i++) {
 		pbn = drm_dp_calc_pbn_mode(test_params[i].rate,
-					   test_params[i].bpp);
+					   test_params[i].bpp,
+					   test_params[i].dsc);
 		FAIL(pbn != test_params[i].expected,
 		     "Expected PBN %d for clock %d bpp %d, got %d\n",
 		     test_params[i].expected, test_params[i].rate,

include/drm/drm_dp_helper.h

@@ -1465,6 +1465,7 @@ int drm_dp_downstream_id(struct drm_dp_aux *aux, char id[6]);
 void drm_dp_downstream_debug(struct seq_file *m, const u8 dpcd[DP_RECEIVER_CAP_SIZE],
 			     const u8 port_cap[4], struct drm_dp_aux *aux);
 
+void drm_dp_remote_aux_init(struct drm_dp_aux *aux);
 void drm_dp_aux_init(struct drm_dp_aux *aux);
 int drm_dp_aux_register(struct drm_dp_aux *aux);
 void drm_dp_aux_unregister(struct drm_dp_aux *aux);
@@ -1522,6 +1523,13 @@ enum drm_dp_quirk {
 	 * The driver should ignore SINK_COUNT during detection.
 	 */
 	DP_DPCD_QUIRK_NO_SINK_COUNT,
+	/**
+	 * @DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD:
+	 *
+	 * The device supports MST DSC despite not supporting Virtual DPCD.
+	 * The DSC caps can be read from the physical aux instead.
+	 */
+	DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD,
 };
 
 /**

include/drm/drm_dp_mst_helper.h

@@ -156,6 +156,8 @@ struct drm_dp_mst_port {
 	 * audio-capable.
 	 */
 	bool has_audio;
+
+	bool fec_capable;
 };
 
 /**
@@ -383,6 +385,7 @@ struct drm_dp_port_number_req {
 
 struct drm_dp_enum_path_resources_ack_reply {
 	u8 port_number;
+	bool fec_capable;
 	u16 full_payload_bw_number;
 	u16 avail_payload_bw_number;
 };
@@ -499,6 +502,8 @@ struct drm_dp_payload {
 struct drm_dp_vcpi_allocation {
 	struct drm_dp_mst_port *port;
 	int vcpi;
+	int pbn;
+	bool dsc_enabled;
 	struct list_head next;
 };
 
@@ -727,8 +732,7 @@ bool drm_dp_mst_port_has_audio(struct drm_dp_mst_topology_mgr *mgr,
 struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
 
 
-int drm_dp_calc_pbn_mode(int clock, int bpp);
+int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc);
-
 
 bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
 			      struct drm_dp_mst_port *port, int pbn, int slots);
@@ -777,7 +781,15 @@ struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_a
 int __must_check
 drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
 			      struct drm_dp_mst_topology_mgr *mgr,
-			      struct drm_dp_mst_port *port, int pbn);
+			      struct drm_dp_mst_port *port, int pbn,
+			      int pbn_div);
+int drm_dp_mst_atomic_enable_dsc(struct drm_atomic_state *state,
+				 struct drm_dp_mst_port *port,
+				 int pbn, int pbn_div,
+				 bool enable);
+int __must_check
+drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state,
+				  struct drm_dp_mst_topology_mgr *mgr);
 int __must_check
 drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 				 struct drm_dp_mst_topology_mgr *mgr,
@@ -789,6 +801,8 @@ int __must_check drm_dp_mst_atomic_check(struct drm_atomic_state *state);
 void drm_dp_mst_get_port_malloc(struct drm_dp_mst_port *port);
 void drm_dp_mst_put_port_malloc(struct drm_dp_mst_port *port);
 
+struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port);
+
 extern const struct drm_private_state_funcs drm_dp_mst_topology_state_funcs;
 
 /**