mb/lenovo/t400: Configure panel-power sequencing

If the panel-power sequencer is not configured, libgfxinit falls back
to very conservative defaults (210ms before EDID is probed). This
results in a boot penalty of >100ms (depending on how long it takes
to probe other ports).

Values are taken from the VBTs already checked in. Untested.

Change-Id: I189776ce8684b4c3c01acd6d2fc433ca33a050d5
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38576
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
diff --git a/src/mainboard/lenovo/t400/devicetree.cb b/src/mainboard/lenovo/t400/devicetree.cb
index 9561dfa..0eea193 100644
--- a/src/mainboard/lenovo/t400/devicetree.cb
+++ b/src/mainboard/lenovo/t400/devicetree.cb
@@ -3,6 +3,11 @@
 	register "gfx.ndid" = "3"
 	register "gfx.did" = "{ 0x80000100, 0x80000240, 0x80000410, 0x80000410, 0x00000005 }"
 
+	register "gpu_panel_power_up_delay" = "250"		# T1+T2: 25ms
+	register "gpu_panel_power_down_delay" = "250"		# T3:    25ms
+	register "gpu_panel_power_backlight_on_delay" = "2500"	# T5:   250ms
+	register "gpu_panel_power_backlight_off_delay" = "2500"	# Tx:   250ms
+	register "gpu_panel_power_cycle_delay" = "3"		# T4:   200ms
 	register "gfx.use_spread_spectrum_clock" = "1"
 
 	device cpu_cluster 0 on