drm/amd/display: Only program MSA_TIMING_PARAM if it changed

Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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 82ee9de..c18f24a 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1183,16 +1183,21 @@ static void enable_stream_features(struct pipe_ctx *pipe_ctx)
 {
        struct dc_stream_state *stream = pipe_ctx->stream;
        struct dc_link *link = stream->sink->link;
-       union down_spread_ctrl downspread;
+       union down_spread_ctrl old_downspread;
+       union down_spread_ctrl new_downspread;
 
        core_link_read_dpcd(link, DP_DOWNSPREAD_CTRL,
-                       &downspread.raw, sizeof(downspread));
+                       &old_downspread.raw, sizeof(old_downspread));
 
-       downspread.bits.IGNORE_MSA_TIMING_PARAM =
+       new_downspread.raw = old_downspread.raw;
+
+       new_downspread.bits.IGNORE_MSA_TIMING_PARAM =
                        (stream->ignore_msa_timing_param) ? 1 : 0;
 
-       core_link_write_dpcd(link, DP_DOWNSPREAD_CTRL,
-                       &downspread.raw, sizeof(downspread));
+       if (new_downspread.raw != old_downspread.raw) {
+               core_link_write_dpcd(link, DP_DOWNSPREAD_CTRL,
+                       &new_downspread.raw, sizeof(new_downspread));
+       }
 }
 
 static enum dc_status enable_link_dp(