I have two external monitors connected to Lenovo T480 via USB-C and HDMI ports (no adapters).
The system only detects builtin and external monitor connected via USB-C, the one connected via HDMI – turns black and nothing happens. But when I unplug USB-C monitor, then HDMI one starts working and the system recognizes it.
Btw closing the lid didn't help – the situation is the same – only USB-C works (HDMI works only if USB-C disconnected).
lspci -v | grep -i vga:
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07) (prog-if 00 [VGA controller])
lshw -c video
*-display
description: VGA compatible controller
product: Intel Corporation
vendor: Intel Corporation
physical id: 2
bus info: pci@0000:00:02.0
version: 07
width: 64 bits
clock: 33MHz
capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
configuration: driver=i915 latency=0
resources: irq:154 memory:e7000000-e7ffffff memory:c0000000-cfffffff ioport:e000(size=64) memory:c0000-dffff
xrandr with USB-C connected (HDMI connected):
Screen 0: minimum 320 x 200, current 3840 x 1200, maximum 8192 x 8192
eDP-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
1920x1080 60.02*+ 60.01 59.97 59.96 59.93 48.00
1680x1050 59.95 59.88
1600x1024 60.17
1400x1050 59.98
1600x900 59.99 59.94 59.95 59.82
1280x1024 60.02
1440x900 59.89
1400x900 59.96 59.88
1280x960 60.00
1440x810 60.00 59.97
1368x768 59.88 59.85
1360x768 59.80 59.96
1280x800 59.99 59.97 59.81 59.91
1152x864 60.00
1280x720 60.00 59.99 59.86 59.74
1024x768 60.04 60.00
960x720 60.00
928x696 60.05
896x672 60.01
1024x576 59.95 59.96 59.90 59.82
960x600 59.93 60.00
960x540 59.96 59.99 59.63 59.82
800x600 60.00 60.32 56.25
840x525 60.01 59.88
864x486 59.92 59.57
800x512 60.17
700x525 59.98
800x450 59.95 59.82
640x512 60.02
720x450 59.89
700x450 59.96 59.88
640x480 60.00 59.94
720x405 59.51 58.99
684x384 59.88 59.85
680x384 59.80 59.96
640x400 59.88 59.98
576x432 60.06
640x360 59.86 59.83 59.84 59.32
512x384 60.00
512x288 60.00 59.92
480x270 59.63 59.82
400x300 60.32 56.34
432x243 59.92 59.57
320x240 60.05
360x202 59.51 59.13
320x180 59.84 59.32
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 59.95*+
1920x1080 60.00
1600x1200 60.00
1680x1050 59.95
1280x1024 60.02
1280x960 60.00
1024x768 60.00
800x600 60.32
640x480 59.94
720x400 70.08
HDMI-2 disconnected (normal left inverted right x axis y axis)
xrandr with USB-C disconnected (HDMI connected):
Screen 0: minimum 320 x 200, current 3840 x 1200, maximum 8192 x 8192
eDP-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 174mm
1920x1080 60.02*+ 60.01 59.97 59.96 59.93 48.00
1680x1050 59.95 59.88
1600x1024 60.17
1400x1050 59.98
1600x900 59.99 59.94 59.95 59.82
1280x1024 60.02
1440x900 59.89
1400x900 59.96 59.88
1280x960 60.00
1440x810 60.00 59.97
1368x768 59.88 59.85
1360x768 59.80 59.96
1280x800 59.99 59.97 59.81 59.91
1152x864 60.00
1280x720 60.00 59.99 59.86 59.74
1024x768 60.04 60.00
960x720 60.00
928x696 60.05
896x672 60.01
1024x576 59.95 59.96 59.90 59.82
960x600 59.93 60.00
960x540 59.96 59.99 59.63 59.82
800x600 60.00 60.32 56.25
840x525 60.01 59.88
864x486 59.92 59.57
800x512 60.17
700x525 59.98
800x450 59.95 59.82
640x512 60.02
720x450 59.89
700x450 59.96 59.88
640x480 60.00 59.94
720x405 59.51 58.99
684x384 59.88 59.85
680x384 59.80 59.96
640x400 59.88 59.98
576x432 60.06
640x360 59.86 59.83 59.84 59.32
512x384 60.00
512x288 60.00 59.92
480x270 59.63 59.82
400x300 60.32 56.34
432x243 59.92 59.57
320x240 60.05
360x202 59.51 59.13
320x180 59.84 59.32
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected primary 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 59.95*+
1920x1080 60.00
1600x1200 60.00
1680x1050 59.88
1280x1024 60.02
1280x960 60.00
1024x768 60.00
800x600 60.32
640x480 59.94
720x400 70.08
Best Answer
I had a similar issue (even though I use Windows) on the T480 using a USB-C hub with HDMI, power and other USB ports.
In my case, the problem was I was using the wrong USB-C port. I was using the left-most USB-C which powers the laptop, instead of the second from the left which is the only Thunderbolt capable one.
Hope this helps, at least someone else who might come across this post.