Dual monitor not detected

Hello,

A dual monitor connected to my HP EliteBook 840 G1 via VGA is not detected.
I found similar posts but could not figure out what to do from the answers.

inxi -Fzx

System:
  Kernel: 5.15.13-200.fc35.x86_64 x86_64 bits: 64 compiler: gcc
  v: 2.37-10.fc35 Desktop: GNOME 41.2
  Distro: Fedora release 35 (Thirty Five)
Machine:
  Type: Laptop System: Hewlett-Packard product: HP EliteBook 840 G1
  v: A3009DD10203 serial: <superuser required>
  Mobo: Hewlett-Packard model: 198F v: KBC Version 15.55
  serial: <superuser required> BIOS: Hewlett-Packard v: L71 Ver. 01.20
  date: 07/28/2014
Battery:
  ID-1: BAT0 charge: 9.1 Wh (100.0%) condition: 9.1/9.1 Wh (100.0%)
  volts: 12.5 min: 11.4 model: Hewlett-Packard Primary status: Full
CPU:
  Info: Dual Core model: Intel Core i7-4600U bits: 64 type: MT MCP
  arch: Haswell rev: 1 cache: L2: 512 KiB
  flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
  bogomips: 21551
  Speed: 1397 MHz min/max: 800/3300 MHz Core speeds (MHz): 1: 1397 2: 1891
  3: 2078 4: 2034
Graphics:
  Device-1: Intel Haswell-ULT Integrated Graphics vendor: Hewlett-Packard
  driver: N/A bus-ID: 00:02.0
  Device-2: Cheng Uei Precision Industry (Foxlink) HP HD Webcam type: USB
  driver: uvcvideo bus-ID: 2-7:5
  Display: x11 server: X.Org 1.20.14 driver: loaded: vesa
  unloaded: fbdev,modesetting resolution: 1920x1080
  OpenGL: renderer: llvmpipe (LLVM 13.0.0 256 bits) v: 4.5 Mesa 21.3.3
  direct render: Yes
Audio:
  Device-1: Intel Haswell-ULT HD Audio vendor: Hewlett-Packard
  driver: snd_hda_intel v: kernel bus-ID: 00:03.0
  Device-2: Intel 8 Series HD Audio vendor: Hewlett-Packard
  driver: snd_hda_intel v: kernel bus-ID: 00:1b.0
  Sound Server-1: ALSA v: k5.15.13-200.fc35.x86_64 running: yes
  Sound Server-2: PipeWire v: 0.3.43 running: yes
Network:
  Device-1: Intel Ethernet I218-LM vendor: Hewlett-Packard driver: e1000e
  v: kernel port: 3080 bus-ID: 00:19.0
  IF: enp0s25 state: up speed: 100 Mbps duplex: full mac: <filter>
  Device-2: Intel Wireless 7260 driver: iwlwifi v: kernel bus-ID: 02:00.0
  IF: wlo1 state: down mac: <filter>
Bluetooth:
  Device-1: Intel Bluetooth wireless interface type: USB driver: btusb
  v: 0.8 bus-ID: 2-3.2:4
  Report: rfkill ID: hci0 rfk-id: 0 state: up address: see --recommends
Drives:
  Local Storage: total: 476.94 GiB used: 12.26 GiB (2.6%)
  ID-1: /dev/sda vendor: Micron model: MTFDDAK512MAY-1AE1ZABHA
  size: 476.94 GiB
Partition:
  ID-1: / size: 475.94 GiB used: 11.99 GiB (2.5%) fs: btrfs dev: /dev/sda2
  ID-2: /boot size: 973.4 MiB used: 270.5 MiB (27.8%) fs: ext4
  dev: /dev/sda1
  ID-3: /home size: 475.94 GiB used: 11.99 GiB (2.5%) fs: btrfs
  dev: /dev/sda2
Swap:
  ID-1: swap-1 type: zram size: 8 GiB used: 0 KiB (0.0%) dev: /dev/zram0
Sensors:
  System Temperatures: cpu: 43.0 C mobo: 0.0 C
  Fan Speeds (RPM): N/A
Info:
  Processes: 465 Uptime: 6m Memory: 15.52 GiB used: 1.93 GiB (12.4%)
  Init: systemd runlevel: 5 Compilers: gcc: 11.2.1 Packages: 3
  note: see --pkg Shell: Bash v: 5.1.8 inxi: 3.3.09

Any help is welcome
Thanks a lot !

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In situations like this, I will always start with the machine firmware - make sure the display output port is enabled and if possible, make it auto active during POST .

Then I will power off the machine, connect the VGA, make sure Monitor input is selected (if your monitor support multiple inputs). Then Power On.

If there is no display in the VGA monitor, try using combination of MediaKeys of the notebook to send output to external monitor.

Once confirmed VGA is working during POST / Firmware setup, then we can proceed to check on Fedora.

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thank you very much for your answer.
I forgot to mention it was working properly on my previous Fedora 20…
So I guess this is a Fedora issue.
Thanks again

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Tested with my old Dell Vostro 3350 notebook. Primary monitor is the built-in LCD. Secondary is external via the VGA port.

For me, it just works - no need to press keys.

Here is my inxi -Fzx output: (I compared the Graphics section with VGA disconnected, VGA output disable by HotKey, I always have 3 devices: Intel, AMD, WebCam.

Compared with your inxi -Fzx, you only have Intel and Webcam. For your EliteBook,
HP EliteBook 840 G1 Notebook PC Product Specifications | HP® Customer Support, the spec there listed there should be a discrete AMD HD8750M.

Why the AMD HD8750M graphics is not enabled by the Kernel in your machine?

inxi -Fzx
System:    Kernel: 5.15.12-200.fc35.x86_64 x86_64 bits: 64 compiler: gcc v: 2.37-10.fc35 Desktop: GNOME 41.2
           Distro: Fedora release 35 (Thirty Five)
Machine:   Type: Portable System: Dell product: Vostro 3350 v: N/A serial: <superuser required>
           Mobo: Dell model: N/A v: A10 serial: <superuser required> BIOS: Dell v: A10 date: 04/08/2014
Battery:   ID-1: BAT0 charge: 45.3 Wh (100.0%) condition: 45.3/82.9 Wh (54.7%) volts: 16.7 min: 14.8 model: SMP DELL 7W5X025
           status: Full
CPU:       Info: Dual Core model: Intel Core i5-2450M bits: 64 type: MT MCP arch: Sandy Bridge rev: 7 cache: L2: 512 KiB
           flags: avx ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 19954
           Speed: 3007 MHz min/max: 800/3100 MHz Core speeds (MHz): 1: 3007 2: 2893 3: 3029 4: 2893
Graphics:  Device-1: Intel 2nd Generation Core Processor Family Integrated Graphics vendor: Dell Vostro 3350 driver: i915
           v: kernel bus-ID: 00:02.0
           Device-2: Advanced Micro Devices [AMD/ATI] Seymour [Radeon HD 6400M/7400M Series] vendor: Dell Vostro 3350
           driver: radeon v: kernel bus-ID: 01:00.0
           Device-3: Microdia Laptop_Integrated_Webcam_HD type: USB driver: uvcvideo bus-ID: 1-1.5:4
           Display: wayland server: X.Org 1.21.1.4 compositor: gnome-shell driver: loaded: radeon
           note: n/a (using device driver) - try sudo/root resolution: 1: 1366x768~60Hz 2: 1920x1200~60Hz
           OpenGL: renderer: Mesa Intel HD Graphics 3000 (SNB GT2) v: 3.3 Mesa 21.3.3 direct render: Yes
Audio:     Device-1: Intel 6 Series/C200 Series Family High Definition Audio vendor: Dell Vostro 3350 driver: snd_hda_intel
           v: kernel bus-ID: 00:1b.0
           Sound Server-1: ALSA v: k5.15.12-200.fc35.x86_64 running: yes
           Sound Server-2: PipeWire v: 0.3.40 running: yes
Network:   Device-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet vendor: Dell Vostro 3350 driver: r8169 v: kernel
           port: d000 bus-ID: 05:00.0
           IF: enp5s0 state: down mac: <filter>
           Device-2: Intel Wireless 7260 driver: iwlwifi v: kernel bus-ID: 09:00.0
           IF: wlp9s0 state: up mac: <filter>
           IF-ID-1: wg2a state: unknown speed: N/A duplex: N/A mac: N/A
Bluetooth: Device-1: Intel Bluetooth wireless interface type: USB driver: btusb v: 0.8 bus-ID: 1-1.4:3
           Report: rfkill ID: hci0 rfk-id: 3 state: up address: see --recommends
Drives:    Local Storage: total: 232.89 GiB used: 6.34 GiB (2.7%)
           ID-1: /dev/sda vendor: Samsung model: SSD 850 EVO 250GB size: 232.89 GiB
Partition: ID-1: / size: 115.44 GiB used: 6.07 GiB (5.3%) fs: btrfs dev: /dev/sda6
           ID-2: /boot size: 973.4 MiB used: 275.2 MiB (28.3%) fs: ext4 dev: /dev/sda5
           ID-3: /home size: 115.44 GiB used: 6.07 GiB (5.3%) fs: btrfs dev: /dev/sda6
Swap:      ID-1: swap-1 type: zram size: 7.66 GiB used: 0 KiB (0.0%) dev: /dev/zram0
Sensors:   System Temperatures: cpu: 63.0 C mobo: N/A gpu: radeon temp: 52.0 C
           Fan Speeds (RPM): cpu: 0
Info:      Processes: 601 Uptime: 6d 20h 15m Memory: 7.66 GiB used: 2.42 GiB (31.6%) Init: systemd runlevel: 5 Compilers:
           gcc: 11.2.1 Packages: N/A note: see --pkg Shell: Bash v: 5.1.8 inxi: 3.3.09

This my dmesg output related to “vga”

dmesg | grep -i vga
[    0.115012] Console: colour VGA+ 80x25
[    0.404783] pci 0000:00:02.0: vgaarb: setting as boot VGA device
[    0.404783] pci 0000:00:02.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
[    0.404783] pci 0000:01:00.0: vgaarb: VGA device added: decodes=io+mem,owns=none,locks=none
[    0.404783] pci 0000:00:02.0: vgaarb: no bridge control possible
[    0.404783] pci 0000:01:00.0: vgaarb: bridge control possible
[    0.404783] vgaarb: loaded
[    2.697088] vga_switcheroo: detected switching method \_SB_.PCI0.GFX0.ATPX handle
[    2.789880] i915 0000:00:02.0: vgaarb: deactivate vga console
[    2.793236] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=none:owns=io+mem
[    2.793265] radeon 0000:01:00.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=none:owns=none
[    3.648624] vga_switcheroo: enabled

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Thanks for your help.
I solved the problem by installing NVIDIA drivers

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