drm: Update MST First Link Slot Information Based on Encoding Format

8b/10b encoding format requires to reserve the first slot for
recording metadata. Real data transmission starts from the second slot,
with a total of available 63 slots available.

In 128b/132b encoding format, metadata is transmitted separately
in LLCP packet before MTP. Real data transmission starts from
the first slot, with a total of 64 slots available.

v2:
* Remove get_mst_link_encoding_cap
* Move total/start slots to mst_state, and copy it to mst_mgr in
atomic_check

Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>

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

@@ -10684,6 +10684,8 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 #if defined(CONFIG_DRM_AMD_DC_DCN)
 	struct dsc_mst_fairness_vars vars[MAX_PIPES];
 #endif
+	struct drm_dp_mst_topology_state *mst_state;
+	struct drm_dp_mst_topology_mgr *mgr;
 
 	trace_amdgpu_dm_atomic_check_begin(state);
 
@@ -10891,6 +10893,32 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev,
 		lock_and_validation_needed = true;
 	}
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+	for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {
+		struct amdgpu_dm_connector *aconnector;
+		struct drm_connector *connector;
+		struct drm_connector_list_iter iter;
+		u8 link_coding_cap;
+
+		if (!mgr->mst_state )
+			continue;
+
+		drm_connector_list_iter_begin(dev, &iter);
+		drm_for_each_connector_iter(connector, &iter) {
+			int id = connector->index;
+
+			if (id == mst_state->mgr->conn_base_id) {
+				aconnector = to_amdgpu_dm_connector(connector);
+				link_coding_cap = dc_link_dp_mst_decide_link_encoding_format(aconnector->dc_link);
+				drm_dp_mst_update_coding_cap(mst_state, link_coding_cap);
+
+				break;
+			}
+		}
+		drm_connector_list_iter_end(&iter);
+
+	}
+#endif
 	/**
 	 * Streams and planes are reset when there are changes that affect
 	 * bandwidth. Anything that affects bandwidth needs to go through

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -3370,7 +3370,7 @@ int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr)
 	struct drm_dp_payload req_payload;
 	struct drm_dp_mst_port *port;
 	int i, j;
-	int cur_slots = 1;
+	int cur_slots = mgr->start_slot;
 	bool skip;
 
 	mutex_lock(&mgr->payload_lock);
@@ -4323,7 +4323,7 @@ int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
 	num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
 
 	/* max. time slots - one slot for MTP header */
-	if (num_slots > 63)
+	if (num_slots > mgr->total_avail_slots)
 		return -ENOSPC;
 	return num_slots;
 }
@@ -4335,7 +4335,7 @@ static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
 	int ret;
 
 	/* max. time slots - one slot for MTP header */
-	if (slots > 63)
+	if (slots > mgr->total_avail_slots)
 		return -ENOSPC;
 
 	vcpi->pbn = pbn;
@@ -4509,6 +4509,18 @@ int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
 }
 EXPORT_SYMBOL(drm_dp_atomic_release_vcpi_slots);
 
+void drm_dp_mst_update_coding_cap(struct drm_dp_mst_topology_state *mst_state, uint8_t link_coding_cap)
+{
+	if (link_coding_cap == DP_CAP_ANSI_128B132B) {
+		mst_state->total_avail_slots = 64;
+		mst_state->start_slot = 0;
+	}
+
+	DRM_DEBUG_KMS("%s coding format on mgr 0x%p\n",
+			(link_coding_cap == DP_CAP_ANSI_128B132B) ? "128b/132b":"8b/10b", mst_state->mgr);
+}
+EXPORT_SYMBOL(drm_dp_mst_update_coding_cap);
+
 /**
  * drm_dp_mst_allocate_vcpi() - Allocate a virtual channel
  * @mgr: manager for this port
@@ -4540,8 +4552,8 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
 
 	ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn, slots);
 	if (ret) {
-		drm_dbg_kms(mgr->dev, "failed to init vcpi slots=%d max=63 ret=%d\n",
-			    DIV_ROUND_UP(pbn, mgr->pbn_div), ret);
+		drm_dbg_kms(mgr->dev, "failed to init vcpi slots=%d max=%d ret=%d\n",
+			    DIV_ROUND_UP(pbn, mgr->pbn_div), mgr->total_avail_slots, ret);
 		drm_dp_mst_topology_put_port(port);
 		goto out;
 	}
@@ -5228,7 +5240,7 @@ 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_vcpi_allocation *vcpi;
-	int avail_slots = 63, payload_count = 0;
+	int avail_slots = mgr->total_avail_slots, payload_count = 0;
 
 	list_for_each_entry(vcpi, &mst_state->vcpis, next) {
 		/* Releasing VCPI is always OK-even if the port is gone */
@@ -5257,7 +5269,7 @@ drm_dp_mst_atomic_check_vcpi_alloc_limit(struct drm_dp_mst_topology_mgr *mgr,
 		}
 	}
 	drm_dbg_atomic(mgr->dev, "[MST MGR:%p] mst state %p VCPI avail=%d used=%d\n",
-		       mgr, mst_state, avail_slots, 63 - avail_slots);
+		       mgr, mst_state, avail_slots, mgr->total_avail_slots - avail_slots);
 
 	return 0;
 }
@@ -5423,6 +5435,10 @@ int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
 			break;
 
 		mutex_lock(&mgr->lock);
+
+		mgr->start_slot = mst_state->start_slot;
+		mgr->total_avail_slots = mst_state->total_avail_slots;
+
 		ret = drm_dp_mst_atomic_check_mstb_bw_limit(mgr->mst_primary,
 							    mst_state);
 		mutex_unlock(&mgr->lock);
@@ -5529,11 +5545,16 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
 	if (!mgr->proposed_vcpis)
 		return -ENOMEM;
 	set_bit(0, &mgr->payload_mask);
+	mgr->total_avail_slots = 63;
+	mgr->start_slot = 1;
 
 	mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
 	if (mst_state == NULL)
 		return -ENOMEM;
 
+	mst_state->total_avail_slots = 63;
+	mst_state->start_slot = 1;
+
 	mst_state->mgr = mgr;
 	INIT_LIST_HEAD(&mst_state->vcpis);
 

include/drm/drm_dp_mst_helper.h

@@ -554,6 +554,8 @@ struct drm_dp_mst_topology_state {
 	struct drm_private_state base;
 	struct list_head vcpis;
 	struct drm_dp_mst_topology_mgr *mgr;
+	u8 total_avail_slots;
+	u8 start_slot;
 };
 
 #define to_dp_mst_topology_mgr(x) container_of(x, struct drm_dp_mst_topology_mgr, base)
@@ -661,6 +663,16 @@ struct drm_dp_mst_topology_mgr {
 	 */
 	int pbn_div;
 
+	/**
+	 * @total_avail_slots: 63 for 8b/10b, 64 for 128/132b
+	 */
+	u8 total_avail_slots;
+
+	/**
+	 * @start_slot: 1 for 8b/10b, 0 for 128/132b
+	 */
+	u8 start_slot;
+
 	/**
 	 * @funcs: Atomic helper callbacks
 	 */
@@ -806,6 +818,7 @@ int drm_dp_mst_get_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp
 
 void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
 
+void drm_dp_mst_update_coding_cap(struct drm_dp_mst_topology_state *mst_state, uint8_t link_coding_cap);
 
 void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
 				struct drm_dp_mst_port *port);