From: Peichen Huang PeiChen.Huang@amd.com

[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 (cherry picked from commit a1c9a1e27022d13c70a14c4faeab6ce293ad043b) 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 --- drivers/gpu/drm/amd/display/dc/core/dc_link.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)

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 63daf6ecbda7..bbaeb6c567d0 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c @@ -2097,6 +2097,7 @@ 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. @@ -2105,7 +2106,9 @@ 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