Commit fa5f99ee authored by Fangzhi Zuo's avatar Fangzhi Zuo Committed by Alex Deucher
Browse files

drm/amd/display: Avoid Read Remote DPCD Many Times 



Reading remote dpcd is time consuming. Instead of reading each byte
one by one, read 16 bytes together.

Reviewed-by: default avatarChiaHsuan (Tom) Chung <chiahsuan.chung@amd.com>
Signed-off-by: default avatarFangzhi Zuo <Jerry.Zuo@amd.com>
Signed-off-by: default avatarWayne Lin <Wayne.Lin@amd.com>
Signed-off-by: default avatarRoman Li <roman.li@amd.com>
Tested-by: default avatarDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 6ec8a5cb

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c

+6 −3
Original line number Diff line number Diff line
@@ -1763,14 +1763,17 @@ static bool dp_get_link_current_set_bw(struct drm_dp_aux *aux, uint32_t *cur_lin 
	union lane_count_set lane_count;

	u8 dp_link_encoding;

	u8 link_bw_set = 0;

	u8 data[16] = {0};



	*cur_link_bw = 0;



	if (drm_dp_dpcd_read(aux, DP_MAIN_LINK_CHANNEL_CODING_SET, &dp_link_encoding, 1) != 1 ||

		drm_dp_dpcd_read(aux, DP_LANE_COUNT_SET, &lane_count.raw, 1) != 1 ||

		drm_dp_dpcd_read(aux, DP_LINK_BW_SET, &link_bw_set, 1) != 1)

	if (drm_dp_dpcd_read(aux, DP_LINK_BW_SET, data, 16) != 16)

		return false;



	dp_link_encoding = data[DP_MAIN_LINK_CHANNEL_CODING_SET - DP_LINK_BW_SET];

	link_bw_set = data[DP_LINK_BW_SET - DP_LINK_BW_SET];

	lane_count.raw = data[DP_LANE_COUNT_SET - DP_LINK_BW_SET];



	switch (dp_link_encoding) {

	case DP_8b_10b_ENCODING:

		link_rate = link_bw_set;