drm/amd/display: determine dp link encoding format from link settings

[how]
Implement a function that determines link encoding format
based on the link settings passed in.
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Reviewed-by: George Shen <George.Shen@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

@@ -4852,4 +4852,11 @@ bool is_edp_ilr_optimization_required(struct dc_link *link, struct dc_crtc_timin
 	return false;
 }
 
+enum dp_link_encoding dp_get_link_encoding_format(const struct dc_link_settings *link_settings)
+{
+	if ((link_settings->link_rate >= LINK_RATE_LOW) &&
+			(link_settings->link_rate <= LINK_RATE_HIGH3))
+		return DP_8b_10b_ENCODING;
+	return DP_UNKNOWN_ENCODING;
+}
 

drivers/gpu/drm/amd/display/dc/dc_dp_types.h

@@ -98,6 +98,11 @@ enum dc_dp_training_pattern {
 	DP_TRAINING_PATTERN_VIDEOIDLE,
 };
 
+enum dp_link_encoding {
+	DP_UNKNOWN_ENCODING = 0,
+	DP_8b_10b_ENCODING = 1,
+};
+
 struct dc_link_settings {
 	enum dc_lane_count lane_count;
 	enum dc_link_rate link_rate;

drivers/gpu/drm/amd/display/dc/inc/dc_link_dp.h

@@ -105,4 +105,5 @@ enum link_training_result dp_check_link_loss_status(
 		struct dc_link *link,
 		const struct link_training_settings *link_training_setting);
 
+enum dp_link_encoding dp_get_link_encoding_format(const struct dc_link_settings *link_settings);
 #endif /* __DC_LINK_DP_H__ */