[PATCH v2 3/3] drm/dp: extract drm_dp_dpcd_clear_payload()

[Jani Nikula <jani.nikula@xxxxxxxxx>]

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

Cc: Lyude Paul <lyude@xxxxxxxxxx>
Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
---
 drivers/gpu/drm/display/drm_dp_helper.c       | 14 ++++++++++++++
 drivers/gpu/drm/display/drm_dp_mst_topology.c |  2 +-
 include/drm/display/drm_dp_helper.h           |  1 +
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 55eca899ce18..da3c8521a7fa 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -849,6 +849,20 @@ int drm_dp_dpcd_write_payload(struct drm_dp_aux *aux,
 }
 EXPORT_SYMBOL(drm_dp_dpcd_write_payload);
 
+/**
+ * drm_dp_dpcd_clear_payload() - Clear the entire VC Payload ID table
+ * @aux: DisplayPort AUX channel
+ *
+ * Clear the entire VC Payload ID table.
+ *
+ * Returns: 0 on success, negative error code on errors.
+ */
+int drm_dp_dpcd_clear_payload(struct drm_dp_aux *aux)
+{
+	return drm_dp_dpcd_write_payload(aux, 0, 0, 0x3f);
+}
+EXPORT_SYMBOL(drm_dp_dpcd_clear_payload);
+
 /**
  * drm_dp_dpcd_poll_act_handled() - Poll for ACT handled status
  * @aux: DisplayPort AUX channel
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 8da39b060f13..5d873bb19dc2 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -3682,7 +3682,7 @@ 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->aux, 0, 0, 0x3f);
+		drm_dp_dpcd_clear_payload(mgr->aux);
 
 		drm_dp_mst_queue_probe_work(mgr);
 
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index 69793815aa82..8f4054a56039 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -569,6 +569,7 @@ int drm_dp_dpcd_read_phy_link_status(struct drm_dp_aux *aux,
 
 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_clear_payload(struct drm_dp_aux *aux);
 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,
-- 
2.39.5