drm/dp: extract drm_dp_dpcd_write_payload()

SST with 128b/132b channel coding needs this too. Extract to a separate
helper, independent of MST.

v2: Clean up kernel-doc a bit

Cc: Lyude Paul <lyude@redhat.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/f626715ba4e348546770750aa3e10fac73a5cbd7.1733238941.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

3 files changed, 62 insertions, 49 deletions

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index fdb55c462d64..55eca899ce18 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -793,6 +793,63 @@ static int read_payload_update_status(struct drm_dp_aux *aux)
 }
 
 /**
+ * drm_dp_dpcd_write_payload() - Write Virtual Channel information to payload table
+ * @aux: DisplayPort AUX channel
+ * @vcpid: Virtual Channel Payload ID
+ * @start_time_slot: Starting time slot
+ * @time_slot_count: Time slot count
+ *
+ * Write the Virtual Channel payload allocation table, checking the payload
+ * update status and retrying as necessary.
+ *
+ * Returns:
+ * 0 on success, negative error otherwise
+ */
+int drm_dp_dpcd_write_payload(struct drm_dp_aux *aux,
+			      int vcpid, u8 start_time_slot, u8 time_slot_count)
+{
+	u8 payload_alloc[3], status;
+	int ret;
+	int retries = 0;
+
+	drm_dp_dpcd_writeb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
+			   DP_PAYLOAD_TABLE_UPDATED);
+
+	payload_alloc[0] = vcpid;
+	payload_alloc[1] = start_time_slot;
+	payload_alloc[2] = time_slot_count;
+
+	ret = drm_dp_dpcd_write(aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
+	if (ret != 3) {
+		drm_dbg_kms(aux->drm_dev, "failed to write payload allocation %d\n", ret);
+		goto fail;
+	}
+
+retry:
+	ret = drm_dp_dpcd_readb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
+	if (ret < 0) {
+		drm_dbg_kms(aux->drm_dev, "failed to read payload table status %d\n", ret);
+		goto fail;
+	}
+
+	if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
+		retries++;
+		if (retries < 20) {
+			usleep_range(10000, 20000);
+			goto retry;
+		}
+		drm_dbg_kms(aux->drm_dev, "status not set after read payload table status %d\n",
+			    status);
+		ret = -EINVAL;
+		goto fail;
+	}
+	ret = 0;
+fail:
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_dpcd_write_payload);
+
+/**
  * drm_dp_dpcd_poll_act_handled() - Poll for ACT handled status
  * @aux: DisplayPort AUX channel
  * @timeout_ms: Timeout in ms
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 2bdbc1eb282b..a426d13a7a36 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -67,9 +67,6 @@ static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
 
 static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port);
 
-static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
-				     int id, u8 start_slot, u8 num_slots);
-
 static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
 				 struct drm_dp_mst_port *port,
 				 int offset, int size, u8 *bytes);
@@ -3263,7 +3260,7 @@ EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
 static int drm_dp_create_payload_at_dfp(struct drm_dp_mst_topology_mgr *mgr,
 					struct drm_dp_mst_atomic_payload *payload)
 {
-	return drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot,
+	return drm_dp_dpcd_write_payload(mgr->aux, payload->vcpi, payload->vc_start_slot,
 					 payload->time_slots);
 }
 
@@ -3294,7 +3291,7 @@ static void drm_dp_destroy_payload_at_remote_and_dfp(struct drm_dp_mst_topology_
 	}
 
 	if (payload->payload_allocation_status == DRM_DP_MST_PAYLOAD_ALLOCATION_DFP)
-		drm_dp_dpcd_write_payload(mgr, payload->vcpi, payload->vc_start_slot, 0);
+		drm_dp_dpcd_write_payload(mgr->aux, payload->vcpi, payload->vc_start_slot, 0);
 }
 
 /**
@@ -3682,7 +3679,7 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
 			goto out_unlock;
 
 		/* Write reset payload */
-		drm_dp_dpcd_write_payload(mgr, 0, 0, 0x3f);
+		drm_dp_dpcd_write_payload(mgr->aux, 0, 0, 0x3f);
 
 		drm_dp_mst_queue_probe_work(mgr);
 
@@ -4679,49 +4676,6 @@ void drm_dp_mst_update_slots(struct drm_dp_mst_topology_state *mst_state, uint8_
 }
 EXPORT_SYMBOL(drm_dp_mst_update_slots);
 
-static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
-				     int id, u8 start_slot, u8 num_slots)
-{
-	u8 payload_alloc[3], status;
-	int ret;
-	int retries = 0;
-
-	drm_dp_dpcd_writeb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
-			   DP_PAYLOAD_TABLE_UPDATED);
-
-	payload_alloc[0] = id;
-	payload_alloc[1] = start_slot;
-	payload_alloc[2] = num_slots;
-
-	ret = drm_dp_dpcd_write(mgr->aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
-	if (ret != 3) {
-		drm_dbg_kms(mgr->dev, "failed to write payload allocation %d\n", ret);
-		goto fail;
-	}
-
-retry:
-	ret = drm_dp_dpcd_readb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
-	if (ret < 0) {
-		drm_dbg_kms(mgr->dev, "failed to read payload table status %d\n", ret);
-		goto fail;
-	}
-
-	if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
-		retries++;
-		if (retries < 20) {
-			usleep_range(10000, 20000);
-			goto retry;
-		}
-		drm_dbg_kms(mgr->dev, "status not set after read payload table status %d\n",
-			    status);
-		ret = -EINVAL;
-		goto fail;
-	}
-	ret = 0;
-fail:
-	return ret;
-}
-
 /**
  * drm_dp_check_act_status() - Polls for ACT handled status.
  * @mgr: manager to use
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index 38eea21d1082..69793815aa82 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -567,6 +567,8 @@ int drm_dp_dpcd_read_phy_link_status(struct drm_dp_aux *aux,
 				     enum drm_dp_phy dp_phy,
 				     u8 link_status[DP_LINK_STATUS_SIZE]);
 
+int drm_dp_dpcd_write_payload(struct drm_dp_aux *aux,
+			      int vcpid, u8 start_time_slot, u8 time_slot_count);
 int drm_dp_dpcd_poll_act_handled(struct drm_dp_aux *aux, int timeout_ms);
 
 bool drm_dp_send_real_edid_checksum(struct drm_dp_aux *aux,