DPI on the laptop's inbuilt screen way off - screen size is 16x10mm. How to fix it?


I’m having issues with setting the laptop’s builtin monitor’s DPI correctly through xorg.conf.

inxi -Fazy:

  Device-1: NVIDIA GA104M [GeForce RTX 3070 Mobile / Max-Q] vendor: Lenovo
    driver: nvidia v: 515.65.01 alternate: nouveau,nvidia_drm non-free: 515.xx+
    status: current (as of 2022-07) arch: Ampere code: GAxxx process: TSMC n7
    (7nm) built: 2020-22 pcie: gen: 3 speed: 8 GT/s lanes: 8 link-max: gen: 4
    speed: 16 GT/s lanes: 16 bus-ID: 01:00.0 chip-ID: 10de:24dd class-ID: 0300
  Device-2: Logitech C920 PRO HD Webcam type: USB
    driver: snd-usb-audio,uvcvideo bus-ID: 1-2.3.3:7 chip-ID: 046d:08e5
    class-ID: 0102 serial: <filter>
  Display: x11 server: X.Org v: 21.1.4 with: Xwayland v: 22.1.3
    compositor: kwin_x11 driver: X: loaded: nvidia gpu: nvidia display-ID: :0
    screens: 1
  Screen-1: 0 s-res: 10160x2160 s-dpi: 58 s-size: 4449x361mm (175.16x14.21")
    s-diag: 4464mm (175.73")
  Monitor-1: DP-0 pos: primary,3-2 res: 2560x1440 dpi: 109
    size: 598x336mm (23.54x13.23") diag: 686mm (27.01") modes: N/A
  Monitor-2: DP-2 pos: 1-3 res: 1200x1920 hz: 60 dpi: 94
    size: 324x518mm (12.76x20.39") diag: 611mm (24.05") modes: N/A
  Monitor-3: DP-4 pos: 2-1 res: 2560x1600 dpi: 4064
    size: 16x10mm (0.63x0.39") diag: 19mm (0.74") modes: N/A
  Monitor-4: HDMI-0 pos: 1-4 res: 3840x2160 dpi: 61
    size: 1600x900mm (62.99x35.43") diag: 1836mm (72.27") modes: N/A
  OpenGL: renderer: NVIDIA GeForce RTX 3070 Laptop GPU/PCIe/SSE2 v: 4.6.0
    NVIDIA 515.65.01 direct render: Yes

As you can see, most of the monitors are set correctly by deafult, however the DP-4 (built-in) does not read the right dimensions and is set to 16x10mm. The HDMI-0 (LG C1 TV) is also wrong at 77 inches, as it should be 55 inches.

Is there a way to fix this issue? I tried adding DisplaySize 344 215 to /etc/X11/xorg.conf, but it did not do anything.