LM 20.1 - Issues detecting second monitor

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helpmefixit
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LM 20.1 - Issues detecting second monitor

Post by helpmefixit »

I recently bought a new lenovo laptop and I have been having issues getting external monitors to work on it. It's an AMD Ryzen 5 4500U with integrated Radeon Graphics.

Initially, I could not get any monitors working. I updated the kernel to 5.8.0-49 through the update manager and got that working. My second monitor is connected via DVI, and that's not working. I am very novice to Ubuntu systems. Any ideas? System info below.

Code: Select all

System:
  Host: matt-hga Kernel: 5.8.0-49-generic x86_64 bits: 64 compiler: N/A 
  Desktop: Cinnamon 4.8.6 Distro: Linux Mint 20.1 Ulyssa 
  base: Ubuntu 20.04 focal 
Machine:
  Type: Laptop System: LENOVO product: 20T60022US v: ThinkPad E14 Gen 2 
  serial: <superuser/root required> 
  Mobo: LENOVO model: 20T60022US serial: <superuser/root required> 
  UEFI: LENOVO v: R1AET34W (1.10 ) date: 12/19/2020 
Battery:
  ID-1: BAT0 charge: 46.8 Wh condition: 46.8/45.0 Wh (104%) 
  model: Sunwoda 5B10X025 status: Charging 
CPU:
  Topology: 6-Core model: AMD Ryzen 5 4500U with Radeon Graphics bits: 64 
  type: MCP arch: Zen rev: 1 L2 cache: 3072 KiB 
  flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm 
  bogomips: 28444 
  Speed: 1397 MHz min/max: 1400/2375 MHz Core speeds (MHz): 1: 1397 2: 1397 
  3: 1397 4: 1334 5: 1400 6: 1347 
Graphics:
  Device-1: AMD Renoir vendor: Lenovo driver: amdgpu v: kernel 
  bus ID: 04:00.0 
  Display: x11 server: X.Org 1.20.9 driver: amdgpu,ati 
  unloaded: fbdev,modesetting,vesa 
  resolution: 1920x1080~60Hz, 1920x1080~60Hz 
  OpenGL: renderer: AMD RENOIR (DRM 3.38.0 5.8.0-49-generic LLVM 11.0.0) 
  v: 4.6 Mesa 20.2.6 direct render: Yes
Last edited by LockBot on Wed Dec 28, 2022 7:16 am, edited 1 time in total.
Reason: Topic automatically closed 6 months after creation. New replies are no longer allowed.
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roblm
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Posts: 5939
Joined: Sun Feb 24, 2013 2:41 pm

Re: LM 20.1 - Issues detecting second monitor

Post by roblm »

Use this command in the Terminal to get more info: xrandr --verbose; echo +; ls /sys/class/drm/
In the Menu at the top, select Edit > Select All and then Edit > Copy

Open the Mint Forum reply window and select </> at the top. Press Ctrl+V to paste the copied lines into a code display window.
helpmefixit
Level 1
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Posts: 7
Joined: Thu Apr 15, 2021 11:24 am

Re: LM 20.1 - Issues detecting second monitor

Post by helpmefixit »

Roblm,

Thanks for your response. In my journey to resolve this issue I have read through many threads where you have contributed. I appreciate it.

NOTE: my initial post was incorrect. It is a DPORT connection not DVI.

Code: Select all

name@matt-hga:~$ xrandr --verbose; echo +; ls /sys/class/drm/
Screen 0: minimum 320 x 200, current 3840 x 1093, maximum 16384 x 16384
eDP connected 1920x1080+1920+13 (0x5a) normal (normal left inverted right x axis y axis) 309mm x 174mm
	Identifier: 0x53
	Timestamp:  19711
	Subpixel:   unknown
	Gamma:      1.0:1.0:1.0
	Brightness: 1.0
	Clones:    
	CRTC:       1
	CRTCs:      1 0 2 3
	Transform:  1.000000 0.000000 0.000000
	            0.000000 1.000000 0.000000
	            0.000000 0.000000 1.000000
	           filter: 
	EDID: 
		00ffffffffffff0006af3d4000000000
		211c0104a51f1178039b859256599029
		20505400000001010101010101010101
		010101010101143780b8703824401010
		3e0035ae100000180000000000000000
		00000000000000000020000000fe0041
		554f0a202020202020202020000000fe
		004231343048414e30342e30200a0097
	GAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	DEGAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	GAMMA_LUT: 0 
		range: (0, 65535)
	CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 
		0 1 
	DEGAMMA_LUT: 0 
		range: (0, 65535)
	TearFree: auto 
		supported: off, on, auto
	HDCP Content Type: HDCP Type0 
		supported: HDCP Type0, HDCP Type1
	Content Protection: Undesired 
		supported: Undesired, Desired, Enabled
	vrr_capable: 0 
		range: (0, 1)
	abm level: 0 
		range: (0, 4)
	max bpc: 16 
		range: (8, 16)
	underscan vborder: 0 
		range: (0, 128)
	underscan hborder: 0 
		range: (0, 128)
	underscan: off 
		supported: off, on, auto
	scaling mode: None 
		supported: None, Full, Center, Full aspect
	link-status: Good 
		supported: Good, Bad
	CONNECTOR_ID: 64 
		supported: 64
	non-desktop: 0 
		range: (0, 1)
  1920x1080 (0x5a) 141.000MHz -HSync -VSync *current +preferred
        h: width  1920 start 1936 end 1952 total 2104 skew    0 clock  67.02KHz
        v: height 1080 start 1083 end 1097 total 1116           clock  60.05Hz
  1680x1050 (0x5b) 141.000MHz -HSync -VSync
        h: width  1680 start 1936 end 1952 total 2104 skew    0 clock  67.02KHz
        v: height 1050 start 1083 end 1097 total 1116           clock  60.05Hz
  1280x1024 (0x5c) 141.000MHz -HSync -VSync
        h: width  1280 start 1936 end 1952 total 2104 skew    0 clock  67.02KHz
        v: height 1024 start 1083 end 1097 total 1116           clock  60.05Hz
  1440x900 (0x5d) 141.000MHz -HSync -VSync
        h: width  1440 start 1936 end 1952 total 2104 skew    0 clock  67.02KHz
        v: height  900 start 1083 end 1097 total 1116           clock  60.05Hz
  1280x800 (0x5e) 141.000MHz -HSync -VSync
        h: width  1280 start 1936 end 1952 total 2104 skew    0 clock  67.02KHz
        v: height  800 start 1083 end 1097 total 1116           clock  60.05Hz
  1280x720 (0x5f) 141.000MHz -HSync -VSync
        h: width  1280 start 1936 end 1952 total 2104 skew    0 clock  67.02KHz
        v: height  720 start 1083 end 1097 total 1116           clock  60.05Hz
  1024x768 (0x60) 141.000MHz -HSync -VSync
        h: width  1024 start 1936 end 1952 total 2104 skew    0 clock  67.02KHz
        v: height  768 start 1083 end 1097 total 1116           clock  60.05Hz
  800x600 (0x61) 141.000MHz -HSync -VSync
        h: width   800 start 1936 end 1952 total 2104 skew    0 clock  67.02KHz
        v: height  600 start 1083 end 1097 total 1116           clock  60.05Hz
  640x480 (0x62) 141.000MHz -HSync -VSync
        h: width   640 start 1936 end 1952 total 2104 skew    0 clock  67.02KHz
        v: height  480 start 1083 end 1097 total 1116           clock  60.05Hz
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
	Identifier: 0x54
	Timestamp:  19711
	Subpixel:   unknown
	Clones:    
	CRTCs:      1 0 2 3
	Transform:  1.000000 0.000000 0.000000
	            0.000000 1.000000 0.000000
	            0.000000 0.000000 1.000000
	           filter: 
	GAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	DEGAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	GAMMA_LUT: 0 
		range: (0, 65535)
	CTM: 0 
	DEGAMMA_LUT: 0 
		range: (0, 65535)
	TearFree: auto 
		supported: off, on, auto
	HDCP Content Type: HDCP Type0 
		supported: HDCP Type0, HDCP Type1
	Content Protection: Undesired 
		supported: Undesired, Desired, Enabled
	vrr_capable: 0 
		range: (0, 1)
	max bpc: 8 
		range: (8, 16)
	underscan vborder: 0 
		range: (0, 128)
	underscan hborder: 0 
		range: (0, 128)
	underscan: off 
		supported: off, on, auto
	scaling mode: None 
		supported: None, Full, Center, Full aspect
	link-status: Good 
		supported: Good, Bad
	CONNECTOR_ID: 71 
		supported: 71
	non-desktop: 0 
		range: (0, 1)
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
	Identifier: 0x55
	Timestamp:  19711
	Subpixel:   unknown
	Clones:    
	CRTCs:      1 0 2 3
	Transform:  1.000000 0.000000 0.000000
	            0.000000 1.000000 0.000000
	            0.000000 0.000000 1.000000
	           filter: 
	GAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	DEGAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	GAMMA_LUT: 0 
		range: (0, 65535)
	CTM: 0 
	DEGAMMA_LUT: 0 
		range: (0, 65535)
	TearFree: auto 
		supported: off, on, auto
	HDCP Content Type: HDCP Type0 
		supported: HDCP Type0, HDCP Type1
	Content Protection: Undesired 
		supported: Undesired, Desired, Enabled
	vrr_capable: 0 
		range: (0, 1)
	max bpc: 8 
		range: (8, 16)
	underscan vborder: 0 
		range: (0, 128)
	underscan hborder: 0 
		range: (0, 128)
	underscan: off 
		supported: off, on, auto
	scaling mode: None 
		supported: None, Full, Center, Full aspect
	link-status: Good 
		supported: Good, Bad
	CONNECTOR_ID: 75 
		supported: 75
	non-desktop: 0 
		range: (0, 1)
DisplayPort-1 connected primary 1920x1080+0+0 (0x63) normal (normal left inverted right x axis y axis) 521mm x 293mm
	Identifier: 0x56
	Timestamp:  19711
	Subpixel:   unknown
	Gamma:      1.0:1.0:1.0
	Brightness: 1.0
	Clones:    
	CRTC:       0
	CRTCs:      1 0 2 3
	Transform:  1.000000 0.000000 0.000000
	            0.000000 1.000000 0.000000
	            0.000000 0.000000 1.000000
	           filter: 
	EDID: 
		00ffffffffffff00418e502401010101
		001b010380341d782a4995a556529f27
		0d5054bfef80b300a9c0950090408180
		010101010101023a801871382d40582c
		450009252100001e662150b051001b30
		4070360009252100001e000000fd0032
		4c0f5211000a202020202020000000fc
		00504c4c323435304d570a20202001ca
		020322f24f900504030207069f141312
		1116150123097f078301000065030c00
		1000023a801871382d40582c45000925
		2100001e011d8018711c1620582c2500
		09252100009e011d007251d01e206e28
		550009252100001e8c0ad08a20e02d10
		103e9600092521000018023a80d07238
		2d40102c458009252100001e0000001f
	GAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	DEGAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	GAMMA_LUT: 0 
		range: (0, 65535)
	CTM: 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 
		0 1 
	DEGAMMA_LUT: 0 
		range: (0, 65535)
	TearFree: auto 
		supported: off, on, auto
	max bpc: 8 
		range: (8, 16)
	HDCP Content Type: HDCP Type0 
		supported: HDCP Type0, HDCP Type1
	Content Protection: Undesired 
		supported: Undesired, Desired, Enabled
	underscan vborder: 0 
		range: (0, 128)
	underscan hborder: 0 
		range: (0, 128)
	underscan: off 
		supported: off, on, auto
	scaling mode: None 
		supported: None, Full, Center, Full aspect
	link-status: Good 
		supported: Good, Bad
	CONNECTOR_ID: 83 
		supported: 83
	non-desktop: 0 
		range: (0, 1)
  1920x1080 (0x63) 148.500MHz +HSync +VSync *current +preferred
        h: width  1920 start 2008 end 2052 total 2200 skew    0 clock  67.50KHz
        v: height 1080 start 1084 end 1089 total 1125           clock  60.00Hz
  1920x1080 (0x64) 148.500MHz +HSync +VSync
        h: width  1920 start 2448 end 2492 total 2640 skew    0 clock  56.25KHz
        v: height 1080 start 1084 end 1089 total 1125           clock  50.00Hz
  1920x1080 (0x65) 148.352MHz +HSync +VSync
        h: width  1920 start 2008 end 2052 total 2200 skew    0 clock  67.43KHz
        v: height 1080 start 1084 end 1089 total 1125           clock  59.94Hz
  1680x1050 (0x66) 119.000MHz +HSync -VSync
        h: width  1680 start 1728 end 1760 total 1840 skew    0 clock  64.67KHz
        v: height 1050 start 1053 end 1059 total 1080           clock  59.88Hz
  1400x1050 (0x67) 101.000MHz +HSync -VSync
        h: width  1400 start 1448 end 1480 total 1560 skew    0 clock  64.74KHz
        v: height 1050 start 1053 end 1057 total 1080           clock  59.95Hz
  1600x900 (0x68) 108.000MHz +HSync +VSync
        h: width  1600 start 1624 end 1704 total 1800 skew    0 clock  60.00KHz
        v: height  900 start  901 end  904 total 1000           clock  60.00Hz
  1280x1024 (0x69) 135.000MHz +HSync +VSync
        h: width  1280 start 1296 end 1440 total 1688 skew    0 clock  79.98KHz
        v: height 1024 start 1025 end 1028 total 1066           clock  75.02Hz
  1280x1024 (0x6a) 108.000MHz +HSync +VSync
        h: width  1280 start 1328 end 1440 total 1688 skew    0 clock  63.98KHz
        v: height 1024 start 1025 end 1028 total 1066           clock  60.02Hz
  1440x900 (0x6b) 88.750MHz +HSync -VSync
        h: width  1440 start 1488 end 1520 total 1600 skew    0 clock  55.47KHz
        v: height  900 start  903 end  909 total  926           clock  59.90Hz
  1360x768 (0x6c) 85.500MHz +HSync +VSync
        h: width  1360 start 1424 end 1536 total 1792 skew    0 clock  47.71KHz
        v: height  768 start  771 end  777 total  795           clock  60.02Hz
  1152x864 (0x6d) 108.000MHz +HSync +VSync
        h: width  1152 start 1216 end 1344 total 1600 skew    0 clock  67.50KHz
        v: height  864 start  865 end  868 total  900           clock  75.00Hz
  1280x720 (0x6e) 74.250MHz +HSync +VSync
        h: width  1280 start 1390 end 1430 total 1650 skew    0 clock  45.00KHz
        v: height  720 start  725 end  730 total  750           clock  60.00Hz
  1280x720 (0x6f) 74.250MHz +HSync +VSync
        h: width  1280 start 1720 end 1760 total 1980 skew    0 clock  37.50KHz
        v: height  720 start  725 end  730 total  750           clock  50.00Hz
  1280x720 (0x70) 74.176MHz +HSync +VSync
        h: width  1280 start 1390 end 1430 total 1650 skew    0 clock  44.96KHz
        v: height  720 start  725 end  730 total  750           clock  59.94Hz
  1024x768 (0x71) 78.750MHz +HSync +VSync
        h: width  1024 start 1040 end 1136 total 1312 skew    0 clock  60.02KHz
        v: height  768 start  769 end  772 total  800           clock  75.03Hz
  1024x768 (0x72) 75.000MHz -HSync -VSync
        h: width  1024 start 1048 end 1184 total 1328 skew    0 clock  56.48KHz
        v: height  768 start  771 end  777 total  806           clock  70.07Hz
  1024x768 (0x73) 65.000MHz -HSync -VSync
        h: width  1024 start 1048 end 1184 total 1344 skew    0 clock  48.36KHz
        v: height  768 start  771 end  777 total  806           clock  60.00Hz
  832x624 (0x74) 57.284MHz -HSync -VSync
        h: width   832 start  864 end  928 total 1152 skew    0 clock  49.73KHz
        v: height  624 start  625 end  628 total  667           clock  74.55Hz
  800x600 (0x75) 50.000MHz +HSync +VSync
        h: width   800 start  856 end  976 total 1040 skew    0 clock  48.08KHz
        v: height  600 start  637 end  643 total  666           clock  72.19Hz
  800x600 (0x76) 49.500MHz +HSync +VSync
        h: width   800 start  816 end  896 total 1056 skew    0 clock  46.88KHz
        v: height  600 start  601 end  604 total  625           clock  75.00Hz
  800x600 (0x77) 40.000MHz +HSync +VSync
        h: width   800 start  840 end  968 total 1056 skew    0 clock  37.88KHz
        v: height  600 start  601 end  605 total  628           clock  60.32Hz
  800x600 (0x78) 36.000MHz +HSync +VSync
        h: width   800 start  824 end  896 total 1024 skew    0 clock  35.16KHz
        v: height  600 start  601 end  603 total  625           clock  56.25Hz
  720x576 (0x79) 27.000MHz -HSync -VSync
        h: width   720 start  732 end  796 total  864 skew    0 clock  31.25KHz
        v: height  576 start  581 end  586 total  625           clock  50.00Hz
  720x480 (0x7a) 27.027MHz -HSync -VSync
        h: width   720 start  736 end  798 total  858 skew    0 clock  31.50KHz
        v: height  480 start  489 end  495 total  525           clock  60.00Hz
  720x480 (0x7b) 27.000MHz -HSync -VSync
        h: width   720 start  736 end  798 total  858 skew    0 clock  31.47KHz
        v: height  480 start  489 end  495 total  525           clock  59.94Hz
  640x480 (0x7c) 31.500MHz -HSync -VSync
        h: width   640 start  656 end  720 total  840 skew    0 clock  37.50KHz
        v: height  480 start  481 end  484 total  500           clock  75.00Hz
  640x480 (0x7d) 31.500MHz -HSync -VSync
        h: width   640 start  664 end  704 total  832 skew    0 clock  37.86KHz
        v: height  480 start  489 end  492 total  520           clock  72.81Hz
  640x480 (0x7e) 30.240MHz -HSync -VSync
        h: width   640 start  704 end  768 total  864 skew    0 clock  35.00KHz
        v: height  480 start  483 end  486 total  525           clock  66.67Hz
  640x480 (0x7f) 25.200MHz -HSync -VSync
        h: width   640 start  656 end  752 total  800 skew    0 clock  31.50KHz
        v: height  480 start  490 end  492 total  525           clock  60.00Hz
  640x480 (0x80) 25.175MHz -HSync -VSync
        h: width   640 start  656 end  752 total  800 skew    0 clock  31.47KHz
        v: height  480 start  490 end  492 total  525           clock  59.94Hz
  720x400 (0x81) 28.320MHz -HSync +VSync
        h: width   720 start  738 end  846 total  900 skew    0 clock  31.47KHz
        v: height  400 start  412 end  414 total  449           clock  70.08Hz
DisplayPort-2 disconnected (normal left inverted right x axis y axis)
	Identifier: 0x57
	Timestamp:  19711
	Subpixel:   unknown
	Clones:    
	CRTCs:      1 0 2 3
	Transform:  1.000000 0.000000 0.000000
	            0.000000 1.000000 0.000000
	            0.000000 0.000000 1.000000
	           filter: 
	GAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	DEGAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	GAMMA_LUT: 0 
		range: (0, 65535)
	CTM: 0 
	DEGAMMA_LUT: 0 
		range: (0, 65535)
	TearFree: auto 
		supported: off, on, auto
	max bpc: 8 
		range: (8, 16)
	HDCP Content Type: HDCP Type0 
		supported: HDCP Type0, HDCP Type1
	Content Protection: Undesired 
		supported: Undesired, Desired, Enabled
	underscan vborder: 0 
		range: (0, 128)
	underscan hborder: 0 
		range: (0, 128)
	underscan: off 
		supported: off, on, auto
	scaling mode: None 
		supported: None, Full, Center, Full aspect
	link-status: Good 
		supported: Good, Bad
	CONNECTOR_ID: 88 
		supported: 88
	non-desktop: 0 
		range: (0, 1)
DisplayPort-3 disconnected (normal left inverted right x axis y axis)
	Identifier: 0x58
	Timestamp:  19711
	Subpixel:   unknown
	Clones:    
	CRTCs:      1 0 2 3
	Transform:  1.000000 0.000000 0.000000
	            0.000000 1.000000 0.000000
	            0.000000 0.000000 1.000000
	           filter: 
	GAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	DEGAMMA_LUT_SIZE: 4096 
		range: (0, -1)
	GAMMA_LUT: 0 
		range: (0, 65535)
	CTM: 0 
	DEGAMMA_LUT: 0 
		range: (0, 65535)
	TearFree: auto 
		supported: off, on, auto
	max bpc: 8 
		range: (8, 16)
	HDCP Content Type: HDCP Type0 
		supported: HDCP Type0, HDCP Type1
	Content Protection: Undesired 
		supported: Undesired, Desired, Enabled
	underscan vborder: 0 
		range: (0, 128)
	underscan hborder: 0 
		range: (0, 128)
	underscan: off 
		supported: off, on, auto
	scaling mode: None 
		supported: None, Full, Center, Full aspect
	link-status: Good 
		supported: Good, Bad
	CONNECTOR_ID: 90 
		supported: 90
	non-desktop: 0 
		range: (0, 1)
+
card0       card0-DP-2  card0-DP-4   card0-HDMI-A-1  ttm
card0-DP-1  card0-DP-3  card0-eDP-1  renderD128      version
mitchell@matt-hga:~$ 
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roblm
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Re: LM 20.1 - Issues detecting second monitor

Post by roblm »

From the info you posted, the external monitor connected to the laptop’s DisplayPort appears to be detected and working at a 1920x1080 resolution.

When you open the Display program, is the monitor visible and turned on?
helpmefixit
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Re: LM 20.1 - Issues detecting second monitor

Post by helpmefixit »

The Display program isn't detecting the monitor. The monitor is displaying "No Signal". The monitor and cord work on a second laptop I have checked it against.
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roblm
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Re: LM 20.1 - Issues detecting second monitor

Post by roblm »

Try this method to force the monitor on.

Use this command to open the grub file: xed admin:///etc/default/grub

Change this line:

Code: Select all

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
To this:

Code: Select all

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video=DP-1:e drm.edid_firmware=DP-1:edid/1920x1080.bin"

Update grub and reboot: sudo update-grub


If there is a problem getting back to the desktop, then press Ctrl+Alt+F1 to enter virtual console tty1. Use this command to open the grub file: sudo nano -t /etc/default/grub

Use the Arrow keys to move the cursor. Remove the changes. Press Ctrl+X to save and exit.
Update grub and reboot. sudo update-grub; reboot

If you can't enter tty1, then select Advanced options > Recovery Mode at the GRUB boot menu. If no menu shows, then hold down the Shift key while starting. In the menu, select “root - drop to root shell prompt ” and press ENTER. Press ENTER again.

Use this command to change the file permissions to read and write: mount -o remount,rw /

Open the grub file: nano -t /etc/default/grub

Remove the changes. Press Ctrl+X to save and exit. Update grub and reboot. update-grub; reboot
helpmefixit
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Re: LM 20.1 - Issues detecting second monitor

Post by helpmefixit »

Roblm,

Before I made my post I had found this suggestion you made in a prior post: viewtopic.php?t=333046

The solution didn't work. Do you think there could be an issue called by the docking port I'm using?
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roblm
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Re: LM 20.1 - Issues detecting second monitor

Post by roblm »

You didn’t mention a docking port was being used. Is it connected to the laptop’s USB3.0 port or USB-C port?
helpmefixit
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Re: LM 20.1 - Issues detecting second monitor

Post by helpmefixit »

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roblm
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Re: LM 20.1 - Issues detecting second monitor

Post by roblm »

The laptop’s USB-C port may or may not have support for video output. This will depend on the laptop’s vender. If you see a symbol for a lightning bolt next to the port, then it definitely supports video. Otherwise you will need to get the laptop’s detailed specifications to see if DisplayPort Alternate Mode or Thunderbolt 3 is supported.
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Re: LM 20.1 - Issues detecting second monitor

Post by helpmefixit »

I know it supports video because I'm running the HDMI connected monitor through it right now. I have used the docking station on another Lenovo laptop and ran dport connections through it just fine as well.
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Re: LM 20.1 - Issues detecting second monitor

Post by roblm »

I assume your laptop is a Lenovo ThinkPad E14 Generation 2. This article says:
There is only a single USB C port (without Thunderbolt), which must be used for charging the laptop,
https://www.notebookcheck.net/Lenovo-Th ... 256.0.html

I think, but am not 100% sure, that some USB-C ports support HDMI Alternate Mode, so can transmit video over a HDMI connection, but do not support DisplayPort Alternate Mode. I admit this is an area of confusion.
https://www.theverge.com/circuitbreaker ... ifications
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Re: LM 20.1 - Issues detecting second monitor

Post by helpmefixit »

roblm,

I have no issue connecting through the same docking station on my home setup with this laptop. I think the issue must be the VGA / DVI outputs on the monitor. The one monitor that is connecting correctly at work is straight HDMI to HDMI. I think there's an issue with the chipset / linux kernel and the VGA/DVI outputs.
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