drm/amd/display: implement T12 compliance

[why]
When OS reboots, and panel is turned off, T12 may not be maintained.
T12 is defined as the interval between VDDC off (occurs at shutdown) and
the next VDDC on (occurs when eDP is POST-ed)

[how]
DC already tracks panel power off time.  Add a DC interface which DM can
call during shutdown.  Ideally this should be as late as possible during
the shutdown sequence so the extra delay is minimal.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Jun Lei <jun.lei@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -203,6 +203,17 @@ static bool program_hpd_filter(const struct dc_link *link)
 	return result;
 }
 
+bool dc_link_wait_for_t12(struct dc_link *link)
+{
+	if (link->connector_signal == SIGNAL_TYPE_EDP && link->dc->hwss.edp_wait_for_T12) {
+		link->dc->hwss.edp_wait_for_T12(link);
+
+		return true;
+	}
+
+	return false;
+}
+
 /**
  * dc_link_detect_sink() - Determine if there is a sink connected
  *

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

@@ -259,6 +259,13 @@ enum dc_status dc_link_reallocate_mst_payload(struct dc_link *link);
 bool dc_link_handle_hpd_rx_irq(struct dc_link *dc_link,
 		union hpd_irq_data *hpd_irq_dpcd_data, bool *out_link_loss);
 
+/*
+ * On eDP links this function call will stall until T12 has elapsed.
+ * If the panel is not in power off state, this function will return
+ * immediately.
+ */
+bool dc_link_wait_for_t12(struct dc_link *link);
+
 enum dc_status read_hpd_rx_irq_data(
 	struct dc_link *link,
 	union hpd_irq_data *irq_data);

drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c

@@ -921,6 +921,37 @@ void dce110_edp_power_control(
 	}
 }
 
+void dce110_edp_wait_for_T12(
+		struct dc_link *link)
+{
+	struct dc_context *ctx = link->ctx;
+
+	if (dal_graphics_object_id_get_connector_id(link->link_enc->connector)
+			!= CONNECTOR_ID_EDP) {
+		BREAK_TO_DEBUGGER();
+		return;
+	}
+
+	if (!link->panel_cntl)
+		return;
+
+	if (!link->panel_cntl->funcs->is_panel_powered_on(link->panel_cntl) &&
+			link->link_trace.time_stamp.edp_poweroff != 0) {
+		unsigned int t12_duration = 500; // Default T12 as per spec
+		unsigned long long current_ts = dm_get_timestamp(ctx);
+		unsigned long long time_since_edp_poweroff_ms =
+				div64_u64(dm_get_elapse_time_in_ns(
+						ctx,
+						current_ts,
+						link->link_trace.time_stamp.edp_poweroff), 1000000);
+
+		t12_duration += link->local_sink->edid_caps.panel_patch.extra_t12_ms; // Add extra T12
+
+		if (time_since_edp_poweroff_ms < t12_duration)
+			msleep(t12_duration - time_since_edp_poweroff_ms);
+	}
+}
+
 /*todo: cloned in stream enc, fix*/
 /*
  * @brief

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.h

@@ -163,6 +163,8 @@ void dcn10_wait_for_mpcc_disconnect(
 void dce110_edp_backlight_control(
 		struct dc_link *link,
 		bool enable);
+void dce110_edp_wait_for_T12(
+		struct dc_link *link);
 void dce110_edp_power_control(
 		struct dc_link *link,
 		bool power_up);

drivers/gpu/drm/amd/display/dc/dcn30/dcn30_init.c

@@ -71,6 +71,7 @@ static const struct hw_sequencer_funcs dcn30_funcs = {
 	.edp_backlight_control = dce110_edp_backlight_control,
 	.edp_power_control = dce110_edp_power_control,
 	.edp_wait_for_hpd_ready = dce110_edp_wait_for_hpd_ready,
+	.edp_wait_for_T12 = dce110_edp_wait_for_T12,
 	.set_cursor_position = dcn10_set_cursor_position,
 	.set_cursor_attribute = dcn10_set_cursor_attribute,
 	.set_cursor_sdr_white_level = dcn10_set_cursor_sdr_white_level,

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

@@ -54,6 +54,7 @@ struct hw_sequencer_funcs {
 	/* Embedded Display Related */
 	void (*edp_power_control)(struct dc_link *link, bool enable);
 	void (*edp_wait_for_hpd_ready)(struct dc_link *link, bool power_up);
+	void (*edp_wait_for_T12)(struct dc_link *link);
 
 	/* Pipe Programming Related */
 	void (*init_hw)(struct dc *dc);