From a1c9a1e27022d13c70a14c4faeab6ce293ad043b Mon Sep 17 00:00:00 2001 From: Peichen Huang Date: Mon, 20 Mar 2023 09:34:23 +0800 Subject: [PATCH] drm/amd/display: skip CLEAR_PAYLOAD_ID_TABLE if device mst_en is 0 [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 Acked-by: Qingqing Zhuo Signed-off-by: Peichen Huang Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/display/dc/link/link_dpms.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c index aa08925..f6c5ee2 100644 --- a/drivers/gpu/drm/amd/display/dc/link/link_dpms.c +++ b/drivers/gpu/drm/amd/display/dc/link/link_dpms.c @@ -2160,6 +2160,7 @@ 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. @@ -2168,7 +2169,9 @@ 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 -- 2.7.4