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  • Activate additional monitor

    From Van Snyder@21:1/5 to All on Mon Jul 21 21:40:01 2025
    I have a desktop system with HDMI graphics on the motherboard and a
    graphics card. Here's the output from inxi -G:

    Device-1: Intel Raptor Lake-S GT1 [UHD Graphics 770] driver: i915 v:
    kernel
    Device-2: NVIDIA GM107GL [Quadro K2200] driver: nouveau v: kernel

    It's running Debian 12.11 with kernel 6.1.140-1.

    If I connect the HDMI monitor before boot, it works. If I connect the
    HDMI monitor after the system is running, it doesn't work.

    I have a laptop that is perfectly happy to start using HDMI that is
    connected after boot. It has only integrated graphics:

    Device-1: Intel Skylake GT2 [HD Graphics 520] driver: i915 v: kernel

    Is there a magic incantation that can be used after boot to find and
    connect the HDMI monitor?

    Or is there a kernel parameter I can put into /etc/default/grub?

    <html><head></head><body><div>I have a desktop system with HDMI graphics on the motherboard and a graphics card. Here's the output from inxi -G:</div><div><br></div><div> Device-1: Intel Raptor Lake-S GT1 [UHD Graphics 770] driver: i915 v: kernel</div><
    Device-2: NVIDIA GM107GL [Quadro K2200] driver: nouveau v: kernel</div><div><br></div><div>It's running Debian 12.11 with kernel 6.1.140-1.</div><div><br></div><div>If I connect the HDMI monitor before boot, it works. If I connect the HDMI monitor
    after the system is running, it doesn't work.</div><div><br></div><div>I have a laptop that is perfectly happy to start using HDMI that is connected after boot. It has only integrated graphics:</div><div><br></div><div>Device-1: Intel Skylake GT2 [HD
    Graphics 520] driver: i915 v: kernel</div><div><br></div><div>Is there a magic incantation that can be used after boot to find and connect the HDMI monitor?</div><div><br></div><div>Or is there a kernel parameter I can put into /etc/default/grub?</div><
    <span></span></div></body></html>

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  • From Charles Curley@21:1/5 to Van Snyder on Mon Jul 21 23:00:01 2025
    On Mon, 21 Jul 2025 12:35:48 -0700
    Van Snyder <[email protected]> wrote:

    I have a desktop system with HDMI graphics on the motherboard and a
    graphics card. Here's the output from inxi -G:

    Device-1: Intel Raptor Lake-S GT1 [UHD Graphics 770] driver: i915 v:
    kernel
    Device-2: NVIDIA GM107GL [Quadro K2200] driver: nouveau v: kernel

    It's running Debian 12.11 with kernel 6.1.140-1.

    If I connect the HDMI monitor before boot, it works. If I connect the
    HDMI monitor after the system is running, it doesn't work.

    If you are running XFCE, take a look at the Display application
    (Applications -> Settings -> Display). I expect other desktops have
    something similar.

    If you don't mind doing a bit of scripting, look at arandr. It will let
    you set up your monitors, then export a script. You can then select a
    script to suit your setup. Or you can call an appropriate one from your desktop/window manager's startup code.

    --
    Does anybody read signatures any more?

    https://charlescurley.com
    https://charlescurley.com/blog/

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  • From Felix Miata@21:1/5 to All on Wed Jul 23 06:10:01 2025
    Van Snyder composed on 2025-07-21 12:35 (UTC-0700):

    I have a desktop system with HDMI graphics on the motherboard and a
    graphics card. Here's the output from inxi -G:

    Device-1: Intel Raptor Lake-S GT1 [UHD Graphics 770] driver: i915 v:
    kernel
    Device-2: NVIDIA GM107GL [Quadro K2200] driver: nouveau v: kernel

    For troubleshooting purposes, inxi -G with no other options is little short
    of useless. With graphics issues, best to provide inxi -GSaz --vs. Bookworm's inxi is broken, so should be upgraded from upstream using the -U switch as superuser after unblocking the -U switch in /etc/inxi.conf, or by upgrading
    the Debian inxi package to the backports version. e.g.:

    # inxi -GSaz --vs --za --hostname
    inxi 3.3.38-00 (2025-04-06)
    System:
    Host: gb970 Kernel: 6.1.0-37-amd64 arch: x86_64 bits: 64 compiler: gcc
    v: 12.2.0 clocksource: tsc avail: hpet,acpi_pm
    parameters: root=LABEL=<filter> ipv6.disable=1 net.ifnames=0
    plymouth.enable=0 noresume consoleblank=0 mitigations=off
    Desktop: TDE (Trinity) v: R14.1.4 tk: Qt v: 3.5.0 wm: Twin v: 3.0
    with: kicker vt: 7 dm: 1: TDM 2: XDM Distro: Debian GNU/Linux 12 (bookworm) Graphics:
    Device-1: NVIDIA GM107GL [Quadro K2200] vendor: Hewlett-Packard
    driver: nouveau v: kernel non-free: 550-570.xx+ status: current (as of
    2025-04; EOL~2026-12-xx) arch: Maxwell code: GMxxx process: TSMC 28nm
    built: 2014-2019 pcie: gen: 2 speed: 5 GT/s lanes: 16 link-max: gen: 3
    speed: 8 GT/s ports: active: DP-1,DP-2,DVI-I-1 empty: none bus-ID: 01:00.0
    chip-ID: 10de:13ba class-ID: 0300 temp: 51.0 C
    Display: x11 server: X.Org v: 1.21.1.7 compositor: Twin v: 3.0 driver: X:
    loaded: modesetting unloaded: fbdev,vesa dri: nouveau gpu: nouveau
    display-ID: :0 screens: 1
    Screen-1: 0 s-res: 3600x2640 s-dpi: 120 s-size: 762x558mm (30.00x21.97")
    s-diag: 944mm (37.18")
    Monitor-1: DP-1 pos: primary,bottom-l model: Acer K272HUL serial: <filter>
    built: 2018 res: mode: 2560x1440 hz: 60 scale: 100% (1) dpi: 109 gamma: 1.2
    size: 598x336mm (23.54x13.23") diag: 686mm (27") ratio: 16:9 modes:
    max: 2560x1440 min: 720x400
    Monitor-2: DP-2 pos: top-left model: NEC EA243WM serial: <filter>
    built: 2011 res: mode: 1920x1200 hz: 60 scale: 100% (1) dpi: 94 gamma: 1.2
    size: 519x324mm (20.43x12.76") diag: 612mm (24.1") ratio: 16:10 modes:
    max: 1920x1200 min: 640x480
    Monitor-3: DVI-I-1 pos: top-right model: Dell P2213 serial: <filter>
    built: 2013 res: mode: 1680x1050 hz: 60 scale: 100% (1) dpi: 90 gamma: 1.2
    size: 473x296mm (18.62x11.65") diag: 558mm (22") ratio: 16:10 modes:
    max: 1680x1050 min: 720x400
    API: EGL v: 1.5 hw: drv: nvidia nouveau platforms: device: 0 drv: nouveau
    device: 1 drv: swrast gbm: drv: nouveau surfaceless: drv: nouveau x11:
    drv: nouveau inactive: wayland
    API: OpenGL v: 4.3 vendor: nouveau mesa v: 22.3.6 glx-v: 1.4 es-v: 3.2
    direct-render: yes renderer: NV117 device-ID: 10de:13ba memory: 3.86 GiB
    unified: no
    API: Vulkan v: 1.3.239 layers: 4 device: 0 type: cpu name: llvmpipe (LLVM
    15.0.6 128 bits) driver: mesa llvmpipe v: 22.3.6 (LLVM 15.0.6)
    device-ID: 10005:0000 surfaces: xcb,xlib
    Info: Tools: api: clinfo, eglinfo, glxinfo, vulkaninfo x11: xdriinfo,
    xdpyinfo, xprop, xrandr
    #

    It's running Debian 12.11 with kernel 6.1.140-1.

    If I connect the HDMI monitor before boot, it works. If I connect the
    HDMI monitor after the system is running, it doesn't work.

    Is there a magic incantation that can be used after boot to find and
    connect the HDMI monitor?

    # ls -gGh /sys/class/drm
    total 0
    lrwxrwxrwx 1 0 Jul 22 23:39 card0 -> ../../devices/pci0000:00/0000:00:02.0/0000:01:00.0/drm/card0
    lrwxrwxrwx 1 0 Jul 22 23:39 card0-DP-1 -> ../../devices/pci0000:00/0000:00:02.0/0000:01:00.0/drm/card0/card0-DP-1
    lrwxrwxrwx 1 0 Jul 22 23:39 card0-DP-2 -> ../../devices/pci0000:00/0000:00:02.0/0000:01:00.0/drm/card0/card0-DP-2
    lrwxrwxrwx 1 0 Jul 22 23:39 card0-DVI-I-1 -> ../../devices/pci0000:00/0000:00:02.0/0000:01:00.0/drm/card0/card0-DVI-I-1
    lrwxrwxrwx 1 0 Jul 22 23:39 renderD128 -> ../../devices/pci0000:00/0000:00:02.0/0000:01:00.0/drm/renderD128
    -r--r--r-- 1 4.0K Jul 22 23:48 version
    #
    What you see above are kernel names for the connectors found. It is often
    the case that kernel names and X names will differ. When this occurs, inxi calls it mapping, e.g.:

    Monitor-1: HDMI-A-2 mapped: HDMI-2 model: Samsung SMS24A850 res: 1920x1200
    hz: 60 dpi: 94 diag: 611mm (24.1")

    Or is there a kernel parameter I can put into /etc/default/grub?

    Have you visited the BIOS while both these GPUs are present in the system?
    GPU configuration there may need some tweaking. Which graphics outputs are
    you connecting your video cables to, NVidia card, motherboard, or both (non- broken inxi -GSaz should show this)?

    Sometimes a kernel cmdline option video= can be useful. <https://www.kernel.org/doc/Documentation/fb/modedb.txt> explains the video= options. e.g., to force the monitor on DP-3 to always be enabled @2560x1440 with 60 refresh, use:

    video=DP-3:2560x1440@60e

    Normally though, video= only works for the vttys. IOW, X does its own thing. Sometimes, not often IME, X will take the hint from a video= parameter.
    --
    Evolution as taught in public schools is, like religion,
    based on faith, not based on science.

    Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

    Felix Miata

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  • From Felix Miata@21:1/5 to All on Wed Jul 23 23:20:01 2025
    Van Snyder composed on 2025-07-23 13:41 (UTC-0700):

    On Wed, 2025-07-23 at 00:03 -0400, Felix Miata wrote:

    For troubleshooting purposes, inxi -G with no other options is little short >> of useless. With graphics issues, best to provide inxi -GSaz --vs. Bookworm's
    inxi is broken, so should be upgraded from upstream using the -U switch as >> superuser after unblocking the -U switch in /etc/inxi.conf, or by upgrading >> the Debian inxi package to the backports version. e.g.:

    # inxi -GSaz --vs --za --hostname

    Thanks for this advice. It revealed what I believe I need to know: What
    is the name of the interface for the display that I want to activate?

    I saw a message that advised putting "video=HDMI-A-1" (which is the
    name revealed by inxi) onto the vmlinuz line using a
    GRUB_CMDLINE_LINUX*= line in /etc/default/grub. Would that make that
    display the only one, or simply make it "exist" along with ones that
    are detected to be working during boot?

    inxi reported

    empty: DP-1, DP-2, HDMI-A-1, HDMI-A-2, HDMI-A-3, HDMI-A-4

    There's only one HDMI connector, so I assume the name I ought (maybe)
    to put into the vmlinuz option is not DP-* or HDMI-A-[234].

    HDMI-A-1 would be kernel name, which is the most likely name you would need to use
    with video=. With video=HDMI-A-1, whatever its continuation that follows will apply exclusively to that output. If you wish the same mode applied on all displays, leave out the output name, e.g. video=2560x1440@60. This is all in <http://www.kernel.org/doc/Documentation/fb/modedb.txt>.
    --
    Evolution as taught in public schools is, like religion,
    based on faith, not based on science.

    Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

    Felix Miata

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  • From Felix Miata@21:1/5 to All on Thu Jul 24 01:00:01 2025
    Van Snyder composed on 2025-07-23 15:21 (UTC-0700):

    This is exactly the advice I needed. Thanks for the reference to <http://www.kernel.org/doc/Documentation/fb/modedb.txt>.

    It was in my first thread reply >18 hours ago: https://lists.debian.org/debian-user/2025/07/msg00556.html

    I did a search for "kernel parameters debian video=" and got many hits,
    but not this one. It was probably on about page 519.

    It's a kernel thing, not specific to Debian. My Grub linu lines more often include
    one or more than not. Also I edit them on a per boot basis nearly as often as not,
    switching video cables among several computers several times most days. My overall
    default is video=1440x900@60, but on some they are more complicated, e.g.: <https://gitlab.freedesktop.org/drm/nouveau/-/issues/385>
    --
    Evolution as taught in public schools is, like religion,
    based on faith, not based on science.

    Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

    Felix Miata

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