[PATCH v2] drm/mst: Enhance MST topology logging

[Eryk Brol]

[why]
MST topology print was missing fec logging and pdt printed
as an int wasn't clear. vcpi and payload info was printed as an
arbitrary series of ints which requires user to know the ordering
of the prints, making the logs difficult to use.

[how]
-add fec logging
-add pdt parsing into strings
-format vcpi and payload info into tables with headings
-clean up topology prints

---

v2: Addressed Lyude's comments
-made helper function return const
-fixed indentation and spacing issues

Signed-off-by: Eryk Brol <eryk.brol at amd.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 59 ++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 932c4641ec3e..de5124ce42cb 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -4720,6 +4720,28 @@ static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr)
 	queue_work(system_long_wq, &mgr->tx_work);
 }
 
+/*
+ * Helper function for parsing DP device types into convenient strings
+ * for use with dp_mst_topology
+ */
+static const char *pdt_to_string(u8 pdt)
+{
+	switch (pdt) {
+	case DP_PEER_DEVICE_NONE:
+		return "NONE";
+	case DP_PEER_DEVICE_SOURCE_OR_SST:
+		return "SOURCE OR SST";
+	case DP_PEER_DEVICE_MST_BRANCHING:
+		return "MST BRANCHING";
+	case DP_PEER_DEVICE_SST_SINK:
+		return "SST SINK";
+	case DP_PEER_DEVICE_DP_LEGACY_CONV:
+		return "DP LEGACY CONV";
+	default:
+		return "ERR";
+	}
+}
+
 static void drm_dp_mst_dump_mstb(struct seq_file *m,
 				 struct drm_dp_mst_branch *mstb)
 {
@@ -4732,9 +4754,20 @@ static void drm_dp_mst_dump_mstb(struct seq_file *m,
 		prefix[i] = '\t';
 	prefix[i] = '\0';
 
-	seq_printf(m, "%smst: %p, %d\n", prefix, mstb, mstb->num_ports);
+	seq_printf(m, "%smstb - [%p]: num_ports: %d\n", prefix, mstb, mstb->num_ports);
 	list_for_each_entry(port, &mstb->ports, next) {
-		seq_printf(m, "%sport: %d: input: %d: pdt: %d, ddps: %d ldps: %d, sdp: %d/%d, %p, conn: %p\n", prefix, port->port_num, port->input, port->pdt, port->ddps, port->ldps, port->num_sdp_streams, port->num_sdp_stream_sinks, port, port->connector);
+		seq_printf(m, "%sport %d - [%p] (%s - %s): ddps: %d, ldps: %d, sdp: %d/%d, fec: %s, conn: %p\n", 
+			   prefix,
+			   port->port_num,
+			   port,
+			   port->input ? "input" : "output",
+			   pdt_to_string(port->pdt),
+			   port->ddps,
+			   port->ldps,
+			   port->num_sdp_streams,
+			   port->num_sdp_stream_sinks,
+			   port->fec_capable ? "true" : "false",
+			   port->connector);
 		if (port->mstb)
 			drm_dp_mst_dump_mstb(m, port->mstb);
 	}
@@ -4787,33 +4820,37 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 	mutex_unlock(&mgr->lock);
 
 	mutex_lock(&mgr->payload_lock);
-	seq_printf(m, "vcpi: %lx %lx %d\n", mgr->payload_mask, mgr->vcpi_mask,
-		mgr->max_payloads);
+	seq_printf(m, "\n*** VCPI Info ***\n");
+	seq_printf(m, "payload_mask: %lx, vcpi_mask: %lx, max_payloads: %d\n", mgr->payload_mask, mgr->vcpi_mask, mgr->max_payloads);
 
+	seq_printf(m, "\n|   idx   |  port # |  vcp_id | # slots |     sink name     |\n");
 	for (i = 0; i < mgr->max_payloads; i++) {
 		if (mgr->proposed_vcpis[i]) {
 			char name[14];
 
 			port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
 			fetch_monitor_name(mgr, port, name, sizeof(name));
-			seq_printf(m, "vcpi %d: %d %d %d sink name: %s\n", i,
-				   port->port_num, port->vcpi.vcpi,
+			seq_printf(m, "%10d%10d%10d%10d%20s\n",
+				   i,
+				   port->port_num,
+				   port->vcpi.vcpi,
 				   port->vcpi.num_slots,
-				   (*name != 0) ? name :  "Unknown");
+				   (*name != 0) ? name : "Unknown");
 		} else
-			seq_printf(m, "vcpi %d:unused\n", i);
+			seq_printf(m, "%6d - Unused\n", i);
 	}
+	seq_printf(m, "\n*** Payload Info ***\n");
+	seq_printf(m, "|   idx   |  state  |  start slot  | # slots |\n");
 	for (i = 0; i < mgr->max_payloads; i++) {
-		seq_printf(m, "payload %d: %d, %d, %d\n",
+		seq_printf(m, "%10d%10d%15d%10d\n",
 			   i,
 			   mgr->payloads[i].payload_state,
 			   mgr->payloads[i].start_slot,
 			   mgr->payloads[i].num_slots);
-
-
 	}
 	mutex_unlock(&mgr->payload_lock);
 
+	seq_printf(m, "\n*** DPCD Info ***\n");
 	mutex_lock(&mgr->lock);
 	if (mgr->mst_primary) {
 		u8 buf[DP_PAYLOAD_TABLE_SIZE];
-- 
2.25.1