$ sudo cat /sys/kernel/debug/dri/0/i915_dp_mst_info 
	mst: ffff880434b94ba0, 0
	port: 3: ddps: 0 ldps: 0, ffff880432484000, conn: ffff880432480000
	port: 2: ddps: 1 ldps: 1, ffff880432484800, conn: ffff880432484400
	port: 1: ddps: 1 ldps: 1, ffff880432485400, conn: ffff880432480800
	port: 0: ddps: 1 ldps: 0, ffff880432485000, conn:           (null)
vcpi: 7
vcpi 0: 1 1 10
vcpi 1: 2 2 10
vcpi 2:unsed
payload 0: 2, 1, 10
payload 1: 2, 11, 10
payload 2: 1, 21, 0
dpcd: 12 14 c4 01 00 15 01 83 02 00 00 00 00 00 04 
faux/mst: 00 01 
mst ctrl: 07 
payload table: 03 01 01 01 01 01 01 01 01 01 01 02 02 02 02 02 02 02 02 02 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00