[PATCH 6.1 118/127] drm/amd/display: skip CLEAR_PAYLOAD_ID_TABLE if device mst_en is 0

Greg Kroah-Hartman
2023-08-09T10:56:39Z

From: Peichen Huang <PeiChen.Huang@amd.com>

commit a1c9a1e27022d13c70a14c4faeab6ce293ad043b upstream.

[Why]
Some dock and mst monitor don't like to receive CLEAR_PAYLOAD_ID_TABLE
when mst_en is set to 0. It doesn't make sense to do so in source
side, either.

[How]
Don't send CLEAR_PAYLOAD_ID_TABLE if mst_en is 0

Reviewed-by: George Shen <George.Shen@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Peichen Huang <PeiChen.Huang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[ 6.1.y doesn't have the file rename from
54618888d1ea7 ("drm/amd/display: break down dc_link.c") ]
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/amd/display/dc/core/dc_link.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -2092,6 +2092,7 @@ static enum dc_status enable_link_dp_mst
struct pipe_ctx *pipe_ctx)
{
struct dc_link *link = pipe_ctx->stream->link;
+ unsigned char mstm_cntl;

/* sink signal type after MST branch is MST. Multiple MST sinks
* share one link. Link DP PHY is enable or training only once.
@@ -2100,7 +2101,9 @@ static enum dc_status enable_link_dp_mst
return DC_OK;

/* clear payload table */
- dm_helpers_dp_mst_clear_payload_allocation_table(link->ctx, link);
+ core_link_read_dpcd(link, DP_MSTM_CTRL, &mstm_cntl, 1);
+ if (mstm_cntl & DP_MST_EN)
+ dm_helpers_dp_mst_clear_payload_allocation_table(link->ctx, link);

/* to make sure the pending down rep can be processed
* before enabling the link