drm/amd/display: Revert "DP link layer test 4.2.1.1 fix due to specs update"

[why]
The change causes some regression in a common use case.
Will need more investigation before fixing the original issue.

[how]
This reverts commit fb8cf277.
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -690,11 +690,9 @@ static bool detect_dp(struct dc_link *link,
 
 	if (sink_caps->transaction_type == DDC_TRANSACTION_TYPE_I2C_OVER_AUX) {
 		sink_caps->signal = SIGNAL_TYPE_DISPLAY_PORT;
-
+		dpcd_set_source_specific_data(link);
 		if (!detect_dp_sink_caps(link))
 			return false;
-		dpcd_set_source_specific_data(link);
-
 		if (is_mst_supported(link)) {
 			sink_caps->signal = SIGNAL_TYPE_DISPLAY_PORT_MST;
 			link->type = dc_connection_mst_branch;

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

@@ -648,17 +648,16 @@ bool dc_link_aux_transfer_with_retries(struct ddc_service *ddc,
 }
 
 
-bool dc_link_aux_try_to_configure_timeout(struct ddc_service *ddc,
+uint32_t dc_link_aux_configure_timeout(struct ddc_service *ddc,
 		uint32_t timeout)
 {
-	bool result = false;
+	uint32_t prev_timeout = 0;
 	struct ddc *ddc_pin = ddc->ddc_pin;
 
-	if (ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en]->funcs->configure_timeout) {
-		ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en]->funcs->configure_timeout(ddc, timeout);
-		result = true;
-	}
-	return result;
+	if (ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en]->funcs->configure_timeout)
+		prev_timeout =
+				ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en]->funcs->configure_timeout(ddc, timeout);
+	return prev_timeout;
 }
 
 /*test only function*/

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

@@ -245,7 +245,7 @@ static uint8_t dc_dp_initialize_scrambling_data_symbols(
 
 static inline bool is_repeater(struct dc_link *link, uint32_t offset)
 {
-	return (link->lttpr_non_transparent_mode && offset != 0);
+	return (!link->is_lttpr_mode_transparent && offset != 0);
 }
 
 static void dpcd_set_lt_pattern_and_lane_settings(
@@ -1038,7 +1038,7 @@ static enum link_training_result perform_clock_recovery_sequence(
 		/* 3. wait receiver to lock-on*/
 		wait_time_microsec = lt_settings->cr_pattern_time;
 
-		if (link->lttpr_non_transparent_mode)
+		if (!link->is_lttpr_mode_transparent)
 			wait_time_microsec = TRAINING_AUX_RD_INTERVAL;
 
 		wait_for_training_aux_rd_interval(
@@ -1268,7 +1268,7 @@ static void configure_lttpr_mode(struct dc_link *link)
 		link->dpcd_caps.lttpr_caps.mode = repeater_mode;
 	}
 
-	if (link->lttpr_non_transparent_mode) {
+	if (!link->is_lttpr_mode_transparent) {
 
 		DC_LOG_HW_LINK_TRAINING("%s\n Set LTTPR to Non Transparent Mode\n", __func__);
 
@@ -1473,7 +1473,7 @@ enum link_training_result dc_link_dp_perform_link_training(
 			&lt_settings);
 
 	/* Configure lttpr mode */
-	if (link->lttpr_non_transparent_mode)
+	if (!link->is_lttpr_mode_transparent)
 		configure_lttpr_mode(link);
 
 	if (link->ctx->dc->work_arounds.lt_early_cr_pattern)
@@ -1489,7 +1489,7 @@ enum link_training_result dc_link_dp_perform_link_training(
 
 	dp_set_fec_ready(link, fec_enable);
 
-	if (link->lttpr_non_transparent_mode) {
+	if (!link->is_lttpr_mode_transparent) {
 
 		/* 2. perform link training (set link training done
 		 *  to false is done as well)
@@ -1757,7 +1757,7 @@ static struct dc_link_settings get_max_link_cap(struct dc_link *link)
 	 * account for lttpr repeaters cap
 	 * notes: repeaters do not snoop in the DPRX Capabilities addresses (3.6.3).
 	 */
-	if (link->lttpr_non_transparent_mode) {
+	if (!link->is_lttpr_mode_transparent) {
 		if (link->dpcd_caps.lttpr_caps.max_lane_count < max_link_cap.lane_count)
 			max_link_cap.lane_count = link->dpcd_caps.lttpr_caps.max_lane_count;
 
@@ -1915,7 +1915,7 @@ bool dp_verify_link_cap(
 	max_link_cap = get_max_link_cap(link);
 
 	/* Grant extended timeout request */
-	if (link->lttpr_non_transparent_mode && link->dpcd_caps.lttpr_caps.max_ext_timeout > 0) {
+	if (!link->is_lttpr_mode_transparent && link->dpcd_caps.lttpr_caps.max_ext_timeout > 0) {
 		uint8_t grant = link->dpcd_caps.lttpr_caps.max_ext_timeout & 0x80;
 
 		core_link_write_dpcd(link, DP_PHY_REPEATER_EXTENDED_WAIT_TIMEOUT, &grant, sizeof(grant));
@@ -3248,7 +3248,17 @@ static bool retrieve_link_cap(struct dc_link *link)
 	uint32_t read_dpcd_retry_cnt = 3;
 	int i;
 	struct dp_sink_hw_fw_revision dp_hw_fw_revision;
-	bool is_lttpr_present = false;
+
+	/* Set default timeout to 3.2ms and read LTTPR capabilities */
+	bool ext_timeout_support = link->dc->caps.extended_aux_timeout_support &&
+			!link->dc->config.disable_extended_timeout_support;
+
+	link->is_lttpr_mode_transparent = true;
+
+	if (ext_timeout_support) {
+		dc_link_aux_configure_timeout(link->ddc,
+					LINK_AUX_DEFAULT_EXTENDED_TIMEOUT_PERIOD);
+	}
 
 	memset(dpcd_data, '\0', sizeof(dpcd_data));
 	memset(lttpr_dpcd_data, '\0', sizeof(lttpr_dpcd_data));
@@ -3257,13 +3267,6 @@ static bool retrieve_link_cap(struct dc_link *link)
 	memset(&edp_config_cap, '\0',
 		sizeof(union edp_configuration_cap));
 
-	/* if extended timeout is supported in hardware,
-	 * default to LTTPR timeout (3.2ms) first as a W/A for DP link layer
-	 * CTS 4.2.1.1 regression introduced by CTS specs requirement update.
-	 */
-	dc_link_aux_try_to_configure_timeout(link->ddc,
-			LINK_AUX_DEFAULT_LTTPR_TIMEOUT_PERIOD);
-
 	status = core_link_read_dpcd(link, DP_SET_POWER,
 				&dpcd_power_state, sizeof(dpcd_power_state));
 
@@ -3290,9 +3293,8 @@ static bool retrieve_link_cap(struct dc_link *link)
 		return false;
 	}
 
-	if (link->dc->caps.extended_aux_timeout_support) {
-		/* By reading LTTPR capability, RX assumes that we will enable LTTPR extended aux timeout if LTTPR is present.
-		 * Therefore, only query LTTPR capability when LTTPR extended aux timeout is supported by hardware */
+	if (ext_timeout_support) {
+
 		status = core_link_read_dpcd(
 				link,
 				DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV,
@@ -3323,20 +3325,19 @@ static bool retrieve_link_cap(struct dc_link *link)
 				lttpr_dpcd_data[DP_PHY_REPEATER_EXTENDED_WAIT_TIMEOUT -
 								DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV];
 
-		is_lttpr_present = (link->dpcd_caps.lttpr_caps.phy_repeater_cnt > 0 &&
+		if (link->dpcd_caps.lttpr_caps.phy_repeater_cnt > 0 &&
 				link->dpcd_caps.lttpr_caps.max_lane_count > 0 &&
 				link->dpcd_caps.lttpr_caps.max_lane_count <= 4 &&
-				link->dpcd_caps.lttpr_caps.revision.raw >= 0x14);
-		if (is_lttpr_present)
-			CONN_DATA_DETECT(link, lttpr_dpcd_data, sizeof(lttpr_dpcd_data), "LTTPR Caps: ");
-	}
-
-	/* decide lttpr non transparent mode */
-	link->lttpr_non_transparent_mode = is_lttpr_present && link->dc->config.allow_lttpr_non_transparent_mode;
-
-	if (!is_lttpr_present)
-		dc_link_aux_try_to_configure_timeout(link->ddc, LINK_AUX_DEFAULT_TIMEOUT_PERIOD);
+				link->dpcd_caps.lttpr_caps.revision.raw >= 0x14) {
+			link->is_lttpr_mode_transparent = false;
+		} else {
+			/*No lttpr reset timeout to its default value*/
+			link->is_lttpr_mode_transparent = true;
+			dc_link_aux_configure_timeout(link->ddc, LINK_AUX_DEFAULT_TIMEOUT_PERIOD);
+		}
 
+		CONN_DATA_DETECT(link, lttpr_dpcd_data, sizeof(lttpr_dpcd_data), "LTTPR Caps: ");
+	}
 
 	{
 		union training_aux_rd_interval aux_rd_interval;

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

@@ -281,7 +281,7 @@ void dp_set_hw_lane_settings(
 {
 	struct link_encoder *encoder = link->link_enc;
 
-	if (link->lttpr_non_transparent_mode && !is_immediate_downstream(link, offset))
+	if (!link->is_lttpr_mode_transparent && !is_immediate_downstream(link, offset))
 		return;
 
 	/* call Encoder to set lane settings */

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

@@ -283,7 +283,7 @@ struct dc_config {
 	bool edp_not_connected;
 	bool force_enum_edp;
 	bool forced_clocks;
-	bool allow_lttpr_non_transparent_mode;
+	bool disable_extended_timeout_support; // Used to disable extended timeout and lttpr feature as well
 	bool multi_mon_pp_mclk_switch;
 	bool disable_dmcu;
 	bool enable_4to1MPC;

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

@@ -101,7 +101,6 @@ struct dc_link {
 	bool aux_access_disabled;
 	bool sync_lt_in_progress;
 	bool is_lttpr_mode_transparent;
-	bool lttpr_non_transparent_mode;
 
 	/* caps is the same as reported_link_cap. link_traing use
 	 * reported_link_cap. Will clean up.  TODO

drivers/gpu/drm/amd/display/dc/dcn21/dcn21_resource.c

@@ -1806,7 +1806,7 @@ static bool dcn21_resource_construct(
 	dc->caps.max_slave_planes = 1;
 	dc->caps.post_blend_color_processing = true;
 	dc->caps.force_dp_tps4_for_cp2520 = true;
-	dc->caps.extended_aux_timeout_support = true;
+	dc->caps.extended_aux_timeout_support = false;
 	dc->caps.dmcub_support = true;
 	dc->caps.is_apu = true;
 

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

@@ -105,7 +105,7 @@ int dc_link_aux_transfer_raw(struct ddc_service *ddc,
 bool dc_link_aux_transfer_with_retries(struct ddc_service *ddc,
 		struct aux_payload *payload);
 
-bool dc_link_aux_try_to_configure_timeout(struct ddc_service *ddc,
+uint32_t dc_link_aux_configure_timeout(struct ddc_service *ddc,
 		uint32_t timeout);
 
 void dal_ddc_service_write_scdc_data(

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

@@ -28,7 +28,7 @@
 
 #define LINK_TRAINING_ATTEMPTS 4
 #define LINK_TRAINING_RETRY_DELAY 50 /* ms */
-#define LINK_AUX_DEFAULT_LTTPR_TIMEOUT_PERIOD 3200 /*us*/
+#define LINK_AUX_DEFAULT_EXTENDED_TIMEOUT_PERIOD 3200 /*us*/
 #define LINK_AUX_DEFAULT_TIMEOUT_PERIOD 552 /*us*/
 
 struct dc_link;