[PATCH 17/20] drm/amd/display: Poll pending down rep before clear payload allocation table

[sunpeng.li at amd.com]

From: Martin Tsai <martin.tsai at amd.com>

[Why]
On current design, driver cannot handle the interrupt for
down reply when link training is processing. The DOWN REQ
send before link training will keep in the pending DOWN REP
state in the queue.
It makes the next DOWN REQ be queued until time out.

[How]
To add a polling sequence before clear payload allocation table
to make sure the pending DOWN REP can be handled.

Signed-off-by: Martin Tsai <martin.tsai at amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu at amd.com>
Acked-by: Leo Li <sunpeng.li at amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 7 +++++++
 drivers/gpu/drm/amd/display/dc/core/dc_link.c             | 5 +++++
 drivers/gpu/drm/amd/display/dc/dm_helpers.h               | 7 +++++++
 3 files changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index e6ab018..cae16b6 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -263,6 +263,13 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
 	return true;
 }
 
+/*
+ * poll pending down reply before clear payload allocation table
+ */
+void dm_helpers_dp_mst_poll_pending_down_reply(
+	struct dc_context *ctx,
+	const struct dc_link *link)
+{}
 
 /*
  * Clear payload allocation table before enable MST DP link.
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index 3dd5f27..8ff5d42 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1467,6 +1467,11 @@ static enum dc_status enable_link_dp_mst(
 	if (link->cur_link_settings.lane_count != LANE_COUNT_UNKNOWN)
 		return DC_OK;
 
+	/* to make sure the pending down rep can be processed
+	 * before clear payload table
+	 */
+	dm_helpers_dp_mst_poll_pending_down_reply(link->ctx, link);
+
 	/* clear payload table */
 	dm_helpers_dp_mst_clear_payload_allocation_table(link->ctx, link);
 
diff --git a/drivers/gpu/drm/amd/display/dc/dm_helpers.h b/drivers/gpu/drm/amd/display/dc/dm_helpers.h
index 5d4527d..e81b243 100644
--- a/drivers/gpu/drm/amd/display/dc/dm_helpers.h
+++ b/drivers/gpu/drm/amd/display/dc/dm_helpers.h
@@ -58,6 +58,13 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
 		bool enable);
 
 /*
+ * poll pending down reply before clear payload allocation table
+ */
+void dm_helpers_dp_mst_poll_pending_down_reply(
+	struct dc_context *ctx,
+	const struct dc_link *link);
+
+/*
  * Clear payload allocation table before enable MST DP link.
  */
 void dm_helpers_dp_mst_clear_payload_allocation_table(
-- 
2.7.4