drm/amd/display: Synchronous DisplayPort Link Training

[WHY]
We require a method to perform synchronous link training.

[HOW]
Sync LT is broken into 3 basic steps.
"Begin" starts the state machine, and resets "preferred" link settings.
"Attempt" will attempt to train the link with a given set of training
parameters.
"End" stops the state machine, and will optionally disable the link phy.
Between "Begin" and "End" DPCD:600h must not be set to "2"
(D3:Powered Down).
Between "Begin" and "End", there may be multiple "Attempts" with different
training parameters.
Signed-off-by: David Galiffi <david.galiffi@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1387,57 +1387,6 @@ void link_destroy(struct dc_link **link)
 	*link = NULL;
 }
 
-static void dpcd_configure_panel_mode(
-	struct dc_link *link,
-	enum dp_panel_mode panel_mode)
-{
-	union dpcd_edp_config edp_config_set;
-	bool panel_mode_edp = false;
-	DC_LOGGER_INIT(link->ctx->logger);
-
-	memset(&edp_config_set, '\0', sizeof(union dpcd_edp_config));
-
-	if (DP_PANEL_MODE_DEFAULT != panel_mode) {
-
-		switch (panel_mode) {
-		case DP_PANEL_MODE_EDP:
-		case DP_PANEL_MODE_SPECIAL:
-			panel_mode_edp = true;
-			break;
-
-		default:
-			break;
-		}
-
-		/*set edp panel mode in receiver*/
-		core_link_read_dpcd(
-			link,
-			DP_EDP_CONFIGURATION_SET,
-			&edp_config_set.raw,
-			sizeof(edp_config_set.raw));
-
-		if (edp_config_set.bits.PANEL_MODE_EDP
-			!= panel_mode_edp) {
-			enum ddc_result result = DDC_RESULT_UNKNOWN;
-
-			edp_config_set.bits.PANEL_MODE_EDP =
-			panel_mode_edp;
-			result = core_link_write_dpcd(
-				link,
-				DP_EDP_CONFIGURATION_SET,
-				&edp_config_set.raw,
-				sizeof(edp_config_set.raw));
-
-			ASSERT(result == DDC_RESULT_SUCESSFULL);
-		}
-	}
-	DC_LOG_DETECTION_DP_CAPS("Link: %d eDP panel mode supported: %d "
-			"eDP panel mode enabled: %d \n",
-			link->link_index,
-			link->dpcd_caps.panel_mode_edp,
-			panel_mode_edp);
-}
-
 static void enable_stream_features(struct pipe_ctx *pipe_ctx)
 {
 	struct dc_stream_state *stream = pipe_ctx->stream;
@@ -1508,7 +1457,7 @@ static enum dc_status enable_link_dp(
 	}
 
 	panel_mode = dp_get_panel_mode(link);
-	dpcd_configure_panel_mode(link, panel_mode);
+	dp_set_panel_mode(link, panel_mode);
 
 	skip_video_pattern = true;
 

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

@@ -55,6 +55,9 @@ void dp_receiver_power_ctrl(struct dc_link *link, bool on)
 
 	state = on ? DP_POWER_STATE_D0 : DP_POWER_STATE_D3;
 
+	if (link->sync_lt_in_progress)
+		return;
+
 	core_link_write_dpcd(link, DP_SET_POWER, &state,
 			sizeof(state));
 }
@@ -245,46 +248,6 @@ void dp_set_hw_lane_settings(
 	encoder->funcs->dp_set_lane_settings(encoder, link_settings);
 }
 
-enum dp_panel_mode dp_get_panel_mode(struct dc_link *link)
-{
-	/* We need to explicitly check that connector
-	 * is not DP. Some Travis_VGA get reported
-	 * by video bios as DP.
-	 */
-	if (link->connector_signal != SIGNAL_TYPE_DISPLAY_PORT) {
-
-		switch (link->dpcd_caps.branch_dev_id) {
-		case DP_BRANCH_DEVICE_ID_2:
-			if (strncmp(
-				link->dpcd_caps.branch_dev_name,
-				DP_VGA_LVDS_CONVERTER_ID_2,
-				sizeof(
-				link->dpcd_caps.
-				branch_dev_name)) == 0) {
-				return DP_PANEL_MODE_SPECIAL;
-			}
-			break;
-		case DP_BRANCH_DEVICE_ID_3:
-			if (strncmp(link->dpcd_caps.branch_dev_name,
-				DP_VGA_LVDS_CONVERTER_ID_3,
-				sizeof(
-				link->dpcd_caps.
-				branch_dev_name)) == 0) {
-				return DP_PANEL_MODE_SPECIAL;
-			}
-			break;
-		default:
-			break;
-		}
-	}
-
-	if (link->dpcd_caps.panel_mode_edp) {
-		return DP_PANEL_MODE_EDP;
-	}
-
-	return DP_PANEL_MODE_DEFAULT;
-}
-
 void dp_set_hw_test_pattern(
 	struct dc_link *link,
 	enum dp_test_pattern test_pattern,

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

@@ -128,7 +128,10 @@ struct dc_link_training_overrides {
 	enum dc_link_spread *downspread;
 	bool *alternate_scrambler_reset;
 	bool *enhanced_framing;
+	bool *mst_enable;
+#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
 	bool *fec_enable;
+#endif
 };
 
 union dpcd_rev {

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

@@ -84,6 +84,7 @@ struct dc_link {
 	bool dp_ss_off;
 	bool link_state_valid;
 	bool aux_access_disabled;
+	bool sync_lt_in_progress;
 
 	/* caps is the same as reported_link_cap. link_traing use
 	 * reported_link_cap. Will clean up.  TODO
@@ -228,6 +229,15 @@ enum link_training_result dc_link_dp_perform_link_training(
 	const struct dc_link_settings *link_setting,
 	bool skip_video_pattern);
 
+bool dc_link_dp_sync_lt_begin(struct dc_link *link);
+
+enum link_training_result dc_link_dp_sync_lt_attempt(
+	struct dc_link *link,
+	struct dc_link_settings *link_setting,
+	struct dc_link_training_overrides *lt_settings);
+
+bool dc_link_dp_sync_lt_end(struct dc_link *link, bool link_down);
+
 void dc_link_dp_enable_hpd(const struct dc_link *link);
 
 void dc_link_dp_disable_hpd(const struct dc_link *link);

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

@@ -62,6 +62,9 @@ bool is_dp_active_dongle(const struct dc_link *link);
 
 void dp_enable_mst_on_sink(struct dc_link *link, bool enable);
 
+enum dp_panel_mode dp_get_panel_mode(struct dc_link *link);
+void dp_set_panel_mode(struct dc_link *link, enum dp_panel_mode panel_mode);
+
 #ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
 void dp_set_fec_ready(struct dc_link *link, bool ready);
 void dp_set_fec_enable(struct dc_link *link, bool enable);

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

@@ -72,8 +72,6 @@ void dp_set_hw_test_pattern(
 	uint8_t *custom_pattern,
 	uint32_t custom_pattern_size);
 
-enum dp_panel_mode dp_get_panel_mode(struct dc_link *link);
-
 void dp_retrain_link_dp_test(struct dc_link *link,
 		struct dc_link_settings *link_setting,
 		bool skip_video_pattern);