[PATCH v2 06/17] drm/display/dp_mst: Sanitize payload iteration in drm_dp_mst_dump_topology()

[Imre Deak <imre.deak@xxxxxxxxx>]

Simplify the loop iterating the payloads by using a helper to get a
payload by its VCPI (keeping the list VCPI sorted). This also removes
the assumption that the biggest VCPI matches the number of payloads
(even though this holds now).

Suggested-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Lyude Paul <lyude@xxxxxxxxxx>
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
---
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 45 ++++++++++++-------
 1 file changed, 28 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 8787df19f428b..0c04b96ae614c 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -4737,6 +4737,18 @@ static void fetch_monitor_name(struct drm_dp_mst_topology_mgr *mgr,
 	kfree(mst_edid);
 }
 
+static struct drm_dp_mst_atomic_payload *
+get_payload_by_vcpi(struct drm_dp_mst_topology_state *mst_state, int vcpi)
+{
+	struct drm_dp_mst_atomic_payload *payload;
+
+	list_for_each_entry(payload, &mst_state->payloads, next)
+		if (payload->vcpi == vcpi)
+			return payload;
+
+	return NULL;
+}
+
 /**
  * drm_dp_mst_dump_topology(): dump topology to seq file.
  * @m: seq_file to dump output to
@@ -4748,7 +4760,6 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 			      struct drm_dp_mst_topology_mgr *mgr)
 {
 	struct drm_dp_mst_topology_state *state;
-	struct drm_dp_mst_atomic_payload *payload;
 	int i, ret;
 
 	mutex_lock(&mgr->lock);
@@ -4768,24 +4779,24 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
 		   state->payload_mask, mgr->max_payloads, state->start_slot, state->pbn_div);
 
 	seq_printf(m, "\n| idx | port | vcpi | slots | pbn | dsc |     sink name     |\n");
-	for (i = 0; i < mgr->max_payloads; i++) {
-		list_for_each_entry(payload, &state->payloads, next) {
-			char name[14];
+	for_each_set_bit(i, (unsigned long *)&state->payload_mask,
+			 BITS_PER_TYPE(state->payload_mask)) {
+		const struct drm_dp_mst_atomic_payload *payload = get_payload_by_vcpi(state, i + 1);
+		char name[14];
 
-			if (payload->vcpi != i + 1 || payload->delete)
-				continue;
+		if (payload->delete)
+			continue;
 
-			fetch_monitor_name(mgr, payload->port, name, sizeof(name));
-			seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s %19s\n",
-				   i,
-				   payload->port->port_num,
-				   payload->vcpi,
-				   payload->vc_start_slot,
-				   payload->vc_start_slot + payload->time_slots - 1,
-				   payload->pbn,
-				   payload->dsc_enabled ? "Y" : "N",
-				   (*name != 0) ? name : "Unknown");
-		}
+		fetch_monitor_name(mgr, payload->port, name, sizeof(name));
+		seq_printf(m, " %5d %6d %6d %02d - %02d %5d %5s %19s\n",
+			   i,
+			   payload->port->port_num,
+			   payload->vcpi,
+			   payload->vc_start_slot,
+			   payload->vc_start_slot + payload->time_slots - 1,
+			   payload->pbn,
+			   payload->dsc_enabled ? "Y" : "N",
+			   (*name != 0) ? name : "Unknown");
 	}
 
 	seq_printf(m, "\n*** DPCD Info ***\n");
-- 
2.37.1