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#1 2018-10-15 12:28:29

katafrakt
Member
From: Kraków
Registered: 2010-06-08
Posts: 22

[Solved] Connecting DP disconnects HDMI (ThinkPad T480)

I have a weird issue with my ThinkPad T480 with Intel integrated card. I'm connecting two monitors – one via Display Port/USB-C and the other via HDMI. Now, when only HDMI one is connected, it works fine. But when I connect the other one, it shows as connected, but now HDMI one is disconnected. When both are plugged at boot, it behaves the same as when DP is connected (i.e. HDMI is not connected).

Best part: it worked ok for last two weeks and I don't see any package updates that could have broken it over the weekend.

xrandr output when only HDMI is connected:

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 310mm x 170mm
   1920x1080     60.02*+  59.93    48.00  
   1680x1050     59.88  
   1400x1050     59.98  
   1600x900      60.00    59.95    59.82  
   1280x1024     60.02  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1368x768      60.00    59.88    59.85  
   1280x800      59.81    59.91  
   1280x720      59.86    60.00    59.74  
   1024x768      60.00  
   1024x576      60.00    59.90    59.82  
   960x540       60.00    59.63    59.82  
   800x600       60.32    56.25  
   864x486       60.00    59.92    59.57  
   640x480       59.94  
   720x405       59.51    60.00    58.99  
   640x360       59.84    59.32    60.00  
DP1 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 550mm x 310mm
   2560x1440     59.95 +
   2048x1152     60.00  
   1920x1200     59.95  
   1920x1080     60.00*   60.00    50.00    59.94    30.00    25.00    24.00    29.97    23.98  
   1920x1080i    60.00    50.00    59.94  
   1600x1200     60.00  
   1680x1050     59.88  
   1280x1024     75.02    60.02  
   1200x960      59.99  
   1152x864      75.00  
   1280x720      60.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00  
   720x576i      50.00  
   720x480       60.00    59.94  
   720x480i      60.00    59.94  
   640x480       75.00    60.00    59.94  
   720x400       70.08  
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

xrandr output after I connect HDMI:

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 310mm x 170mm
   1920x1080     60.02*+  59.93    48.00  
   1680x1050     59.88  
   1400x1050     59.98  
   1600x900      60.00    59.95    59.82  
   1280x1024     60.02  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1368x768      60.00    59.88    59.85  
   1280x800      59.81    59.91  
   1280x720      59.86    60.00    59.74  
   1024x768      60.00  
   1024x576      60.00    59.90    59.82  
   960x540       60.00    59.63    59.82  
   800x600       60.32    56.25  
   864x486       60.00    59.92    59.57  
   640x480       59.94  
   720x405       59.51    60.00    58.99  
   640x360       59.84    59.32    60.00  
DP1 disconnected (normal left inverted right x axis y axis)
DP2 connected (normal left inverted right x axis y axis)
   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  
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
  1920x1080 (0x4b) 148.500MHz +HSync +VSync
        h: width  1920 start 2008 end 2052 total 2200 skew    0 clock  67.50KHz
        v: height 1080 start 1082 end 1087 total 1125           clock  60.00Hz

BTW I have no clue what this "VIRTUAL1" is, but it started to show only recently.

I looks like something is turning off HDMI when DP is plugged, but I don't really know where to start looking. Nothing shows up in dmesg or journalctl.

Also, there are no errors in Xorg.log.

Anyone has some clue?

EDIT:

Not sure if that matters, but after fresh boot with both cables connected xrandr output is slightly different (no info about this VIRTUAL1):

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 310mm x 170mm
   1920x1080     60.02*+  59.93    48.00  
   1680x1050     59.88  
   1400x1050     59.98  
   1600x900      60.00    59.95    59.82  
   1280x1024     60.02  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1368x768      60.00    59.88    59.85  
   1280x800      59.81    59.91  
   1280x720      59.86    60.00    59.74  
   1024x768      60.00  
   1024x576      60.00    59.90    59.82  
   960x540       60.00    59.63    59.82  
   800x600       60.32    56.25  
   864x486       60.00    59.92    59.57  
   640x480       59.94  
   720x405       59.51    60.00    58.99  
   640x360       59.84    59.32    60.00  
DP1 disconnected (normal left inverted right x axis y axis)
DP2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 520mm x 320mm
   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  
HDMI1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

Last edited by katafrakt (2018-10-18 09:33:14)

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#2 2018-10-15 12:37:07

katafrakt
Member
From: Kraków
Registered: 2010-06-08
Posts: 22

Re: [Solved] Connecting DP disconnects HDMI (ThinkPad T480)

Perhaps relevant section from Xorg.log:

[     6.195] (WW) Falling back to old probe method for fbdev
[     6.195] (II) Loading sub module "fbdevhw"
[     6.195] (II) LoadModule: "fbdevhw"
[     6.195] (II) Loading /usr/lib/xorg/modules/libfbdevhw.so
[     6.196] (II) Module fbdevhw: vendor="X.Org Foundation"
[     6.196] 	compiled for 1.20.1, module version = 0.0.2
[     6.196] 	ABI class: X.Org Video Driver, version 24.0
[     6.197] (--) intel(0): gen9 engineering sample
[     6.197] (--) intel(0): CPU: x86-64, sse2, sse3, ssse3, sse4.1, sse4.2, avx, avx2; using a maximum of 4 threads
[     6.197] (II) intel(0): Creating default Display subsection in Screen section
	"Default Screen Section" for depth/fbbpp 24/32
[     6.197] (==) intel(0): Depth 24, (--) framebuffer bpp 32
[     6.197] (==) intel(0): RGB weight 888
[     6.197] (==) intel(0): Default visual is TrueColor
[     6.199] (II) intel(0): Output eDP1 has no monitor section
[     6.199] (**) intel(0): Found backlight control interface intel_backlight (type 'raw') for output eDP1
[     6.199] (II) intel(0): Enabled output eDP1
[     6.199] (II) intel(0): Output DP1 has no monitor section
[     6.199] (II) intel(0): Enabled output DP1
[     6.199] (II) intel(0): Output HDMI1 has no monitor section
[     6.200] (II) intel(0): Enabled output HDMI1
[     6.200] (II) intel(0): Output DP2 has no monitor section
[     6.200] (II) intel(0): Enabled output DP2
[     6.200] (II) intel(0): Output HDMI2 has no monitor section
[     6.200] (II) intel(0): Enabled output HDMI2
[     6.200] (--) intel(0): Using a maximum size of 256x256 for hardware cursors
[     6.201] (II) intel(0): Output VIRTUAL1 has no monitor section
[     6.201] (II) intel(0): Enabled output VIRTUAL1
[     6.201] (--) intel(0): Output eDP1 using initial mode 1920x1080 on pipe 0
[     6.201] (--) intel(0): Output DP2 using initial mode 1920x1080 on pipe 1
[     6.201] (==) intel(0): TearFree enabled
[     6.201] (==) intel(0): Using gamma correction (1.0, 1.0, 1.0)
[     6.201] (==) intel(0): DPI set to (96, 96)

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#3 2018-10-16 08:54:20

katafrakt
Member
From: Kraków
Registered: 2010-06-08
Posts: 22

Re: [Solved] Connecting DP disconnects HDMI (ThinkPad T480)

This is result of udevadm monitor the moment when DP cable is plugged in:

KERNEL[11393.496390] change   /devices/platform/USBC000:00/typec/port0 (typec)
KERNEL[11393.496498] change   /devices/platform/USBC000:00/typec/port0 (typec)
KERNEL[11393.496579] change   /devices/platform/USBC000:00/typec/port0 (typec)
KERNEL[11393.496634] add      /devices/platform/USBC000:00/typec/port0/port0-partner (typec)
UDEV  [11393.502191] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [11393.504868] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [11393.505642] change   /devices/platform/USBC000:00/typec/port0 (typec)
UDEV  [11393.506436] add      /devices/platform/USBC000:00/typec/port0/port0-partner (typec)
KERNEL[11395.335490] change   /devices/pci0000:00/0000:00:02.0/drm/card0 (drm)
UDEV  [11395.351379] change   /devices/pci0000:00/0000:00:02.0/drm/card0 (drm)
KERNEL[11395.536884] change   /devices/pci0000:00/0000:00:02.0/drm/card0 (drm)
UDEV  [11395.544292] change   /devices/pci0000:00/0000:00:02.0/drm/card0 (drm)

Last edited by katafrakt (2018-10-16 09:01:11)

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#4 2018-10-18 06:59:02

katafrakt
Member
From: Kraków
Registered: 2010-06-08
Posts: 22

Re: [Solved] Connecting DP disconnects HDMI (ThinkPad T480)

FYI this was hardware issue - apparently you cannot have both back USB-C and HDMI working at the same time in this laptop model. But works when DP cable was plugged to the other port.

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