drm/amd/display: Add dpia display mode validation logic

[Why]
If bandwidth allocation feature is enabled, connection manager wont
limit the dp tunnel bandwidth. So, need to do display mode validation
for streams on dpia links to avoid oversubscription of dp tunnel
bandwidth.

[How]
- To read non reduced link rate and lane count and update
  reported link capability.
- To calculate the bandwidth required for streams of dpia links
  per host router and validate against the allocated bandwidth for
  the host router.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: PeiChen Huang <peichen.huang@amd.com>
Reviewed-by: Aric Cyr <aric.cyr@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 93 insertions, 37 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c
index d6e1f969bfd5..a7aa8c9da868 100644
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c
@@ -59,6 +59,7 @@ static void reset_bw_alloc_struct(struct dc_link *link)
 	link->dpia_bw_alloc_config.estimated_bw = 0;
 	link->dpia_bw_alloc_config.bw_granularity = 0;
 	link->dpia_bw_alloc_config.response_ready = false;
+	link->dpia_bw_alloc_config.sink_allocated_bw = 0;
 }
 
 #define BW_GRANULARITY_0 4 // 0.25 Gbps
@@ -104,6 +105,32 @@ static int get_estimated_bw(struct dc_link *link)
 	return bw_estimated_bw * (Kbps_TO_Gbps / link->dpia_bw_alloc_config.bw_granularity);
 }
 
+static int get_non_reduced_max_link_rate(struct dc_link *link)
+{
+	uint8_t nrd_max_link_rate = 0;
+
+	core_link_read_dpcd(
+			link,
+			DP_TUNNELING_MAX_LINK_RATE,
+			&nrd_max_link_rate,
+			sizeof(uint8_t));
+
+	return nrd_max_link_rate;
+}
+
+static int get_non_reduced_max_lane_count(struct dc_link *link)
+{
+	uint8_t nrd_max_lane_count = 0;
+
+	core_link_read_dpcd(
+			link,
+			DP_TUNNELING_MAX_LANE_COUNT,
+			&nrd_max_lane_count,
+			sizeof(uint8_t));
+
+	return nrd_max_lane_count;
+}
+
 /*
  * Read all New BW alloc configuration ex: estimated_bw, allocated_bw,
  * granuality, Driver_ID, CM_Group, & populate the BW allocation structs
@@ -111,13 +138,20 @@ static int get_estimated_bw(struct dc_link *link)
  */
 static void init_usb4_bw_struct(struct dc_link *link)
 {
-	// Init the known values
+	reset_bw_alloc_struct(link);
+
+	/* init the known values */
 	link->dpia_bw_alloc_config.bw_granularity = get_bw_granularity(link);
 	link->dpia_bw_alloc_config.estimated_bw = get_estimated_bw(link);
+	link->dpia_bw_alloc_config.nrd_max_link_rate = get_non_reduced_max_link_rate(link);
+	link->dpia_bw_alloc_config.nrd_max_lane_count = get_non_reduced_max_lane_count(link);
 
 	DC_LOG_DEBUG("%s: bw_granularity(%d), estimated_bw(%d)\n",
 		__func__, link->dpia_bw_alloc_config.bw_granularity,
 		link->dpia_bw_alloc_config.estimated_bw);
+	DC_LOG_DEBUG("%s: nrd_max_link_rate(%d), nrd_max_lane_count(%d)\n",
+		__func__, link->dpia_bw_alloc_config.nrd_max_link_rate,
+		link->dpia_bw_alloc_config.nrd_max_lane_count);
 }
 
 static uint8_t get_lowest_dpia_index(struct dc_link *link)
@@ -142,39 +176,50 @@ static uint8_t get_lowest_dpia_index(struct dc_link *link)
 }
 
 /*
- * Get the Max Available BW or Max Estimated BW for each Host Router
+ * Get the maximum dp tunnel banwidth of host router
  *
- * @link: pointer to the dc_link struct instance
- * @type: ESTIMATD BW or MAX AVAILABLE BW
+ * @dc: pointer to the dc struct instance
+ * @hr_index: host router index
  *
- * return: response_ready flag from dc_link struct
+ * return: host router maximum dp tunnel bandwidth
  */
-static int get_host_router_total_bw(struct dc_link *link, uint8_t type)
+static int get_host_router_total_dp_tunnel_bw(const struct dc *dc, uint8_t hr_index)
 {
-	const struct dc *dc_struct = link->dc;
-	uint8_t lowest_dpia_index = get_lowest_dpia_index(link);
-	uint8_t idx = (link->link_index - lowest_dpia_index) / 2, idx_temp = 0;
-	struct dc_link *link_temp;
+	uint8_t lowest_dpia_index = get_lowest_dpia_index(dc->links[0]);
+	uint8_t hr_index_temp = 0;
+	struct dc_link *link_dpia_primary, *link_dpia_secondary;
 	int total_bw = 0;
-	int i;
-
-	for (i = 0; i < MAX_PIPES * 2; ++i) {
 
-		if (!dc_struct->links[i] || dc_struct->links[i]->ep_type != DISPLAY_ENDPOINT_USB4_DPIA)
-			continue;
+	for (uint8_t i = 0; i < MAX_PIPES * 2; ++i) {
 
-		link_temp = dc_struct->links[i];
-		if (!link_temp || !link_temp->hpd_status)
+		if (!dc->links[i] || dc->links[i]->ep_type != DISPLAY_ENDPOINT_USB4_DPIA)
 			continue;
 
-		idx_temp = (link_temp->link_index - lowest_dpia_index) / 2;
-
-		if (idx_temp == idx) {
-
-			if (type == HOST_ROUTER_BW_ESTIMATED)
-				total_bw += link_temp->dpia_bw_alloc_config.estimated_bw;
-			else if (type == HOST_ROUTER_BW_ALLOCATED)
-				total_bw += link_temp->dpia_bw_alloc_config.sink_allocated_bw;
+		hr_index_temp = (dc->links[i]->link_index - lowest_dpia_index) / 2;
+
+		if (hr_index_temp == hr_index) {
+			link_dpia_primary = dc->links[i];
+			link_dpia_secondary = dc->links[i + 1];
+
+			/**
+			 * If BW allocation enabled on both DPIAs, then
+			 * HR BW = Estimated(dpia_primary) + Allocated(dpia_secondary)
+			 * otherwise HR BW = Estimated(bw alloc enabled dpia)
+			 */
+			if ((link_dpia_primary->hpd_status &&
+				link_dpia_primary->dpia_bw_alloc_config.bw_alloc_enabled) &&
+				(link_dpia_secondary->hpd_status &&
+				link_dpia_secondary->dpia_bw_alloc_config.bw_alloc_enabled)) {
+				total_bw += link_dpia_primary->dpia_bw_alloc_config.estimated_bw +
+					link_dpia_secondary->dpia_bw_alloc_config.sink_allocated_bw;
+			} else if (link_dpia_primary->hpd_status &&
+					link_dpia_primary->dpia_bw_alloc_config.bw_alloc_enabled) {
+				total_bw = link_dpia_primary->dpia_bw_alloc_config.estimated_bw;
+			} else if (link_dpia_secondary->hpd_status &&
+				link_dpia_secondary->dpia_bw_alloc_config.bw_alloc_enabled) {
+				total_bw += link_dpia_secondary->dpia_bw_alloc_config.estimated_bw;
+			}
+			break;
 		}
 	}
 
@@ -194,7 +239,6 @@ static void dpia_bw_alloc_unplug(struct dc_link *link)
 	if (link) {
 		DC_LOG_DEBUG("%s: resetting bw alloc config for link(%d)\n",
 			__func__, link->link_index);
-		link->dpia_bw_alloc_config.sink_allocated_bw = 0;
 		reset_bw_alloc_struct(link);
 	}
 }
@@ -397,7 +441,7 @@ int dpia_handle_usb4_bandwidth_allocation_for_link(struct dc_link *link, int pea
 		if (!timeout)
 			ret = 0;// ERROR TIMEOUT waiting for response for allocating bw
 		else if (link->dpia_bw_alloc_config.sink_allocated_bw > 0)
-			ret = get_host_router_total_bw(link, HOST_ROUTER_BW_ALLOCATED);
+			ret = link->dpia_bw_alloc_config.sink_allocated_bw;
 	}
 	//2. Cold Unplug
 	else if (!link->hpd_status)
@@ -439,29 +483,41 @@ out:
 bool dpia_validate_usb4_bw(struct dc_link **link, int *bw_needed_per_dpia, const unsigned int num_dpias)
 {
 	bool ret = true;
-	int bw_needed_per_hr[MAX_HR_NUM] = { 0, 0 };
-	uint8_t lowest_dpia_index = 0, dpia_index = 0;
-	uint8_t i;
+	int bw_needed_per_hr[MAX_HR_NUM] = { 0, 0 }, host_router_total_dp_bw = 0;
+	uint8_t lowest_dpia_index, i, hr_index;
 
 	if (!num_dpias || num_dpias > MAX_DPIA_NUM)
 		return ret;
 
-	//Get total Host Router BW & Validate against each Host Router max BW
+	lowest_dpia_index = get_lowest_dpia_index(link[0]);
+
+	/* get total Host Router BW with granularity for the given modes */
 	for (i = 0; i < num_dpias; ++i) {
+		int granularity_Gbps = 0;
+		int bw_granularity = 0;
 
 		if (!link[i]->dpia_bw_alloc_config.bw_alloc_enabled)
 			continue;
 
-		lowest_dpia_index = get_lowest_dpia_index(link[i]);
 		if (link[i]->link_index < lowest_dpia_index)
 			continue;
 
-		dpia_index = (link[i]->link_index - lowest_dpia_index) / 2;
-		bw_needed_per_hr[dpia_index] += bw_needed_per_dpia[i];
-		if (bw_needed_per_hr[dpia_index] > get_host_router_total_bw(link[i], HOST_ROUTER_BW_ALLOCATED)) {
+		granularity_Gbps = (Kbps_TO_Gbps / link[i]->dpia_bw_alloc_config.bw_granularity);
+		bw_granularity = (bw_needed_per_dpia[i] / granularity_Gbps) * granularity_Gbps +
+				((bw_needed_per_dpia[i] % granularity_Gbps) ? granularity_Gbps : 0);
 
-			ret = false;
-			break;
+		hr_index = (link[i]->link_index - lowest_dpia_index) / 2;
+		bw_needed_per_hr[hr_index] += bw_granularity;
+	}
+
+	/* validate against each Host Router max BW */
+	for (hr_index = 0; hr_index < MAX_HR_NUM; ++hr_index) {
+		if (bw_needed_per_hr[hr_index]) {
+			host_router_total_dp_bw = get_host_router_total_dp_tunnel_bw(link[0]->dc, hr_index);
+			if (bw_needed_per_hr[hr_index] > host_router_total_dp_bw) {
+				ret = false;
+				break;
+			}
 		}
 	}