I do know that Linux X11 (amdgpu kernel driver, modesetting X11 driver) tends to drive my DVI 1080p display with too high of a pixel clock (too large blanking intervals) when connected over a HDMI-to-DVI cable from my GPU. I believe this is because there's actually a duplication of mode selection logic between the amdgpu kernel driver and X11. I've reported another (system hang) amdgpu/X11 resolution bug at https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu... with no progress towards being resolved so far. Neither bug appears on Wayland, but mainstream Wayland desktop environments (KDE/GNOME) do not allow adding custom resolutions through xrandr without overriding EDID files and either rebooting for the kernel to see it, or touching files in /proc/ (untested).
Re:Hacking the LG Monitor's EDID
by nyanpasu64 on Wednesday August 30, 2023 @02:40PM
(#37326847)
I have experienced pixel clock errors on Linux, but can't say in this case if the monitor, cable, or GPU is unable to handle full resolution at 144hz. The CTA-861 (HDMI metadata) block contains a mode "3440x1440 99.990 Hz", or 1440p100 with a pixel clock of 543.5 MHz. I don't know if this 100hz mode functions on Windows or not. The DIsplayID block instead contains a 144hz mode with a pixel clock of 799.750 MHz. Both of these modes may be within DisplayPort bandwidth limits or not, depending on the link rate and bits per pixel (this EDID says "Bits per primary color channel: 10"), and may also be supported by the display or not.
Not sure about Mac, but you can do the same on Windows. It's a bit different world and sometimes overly complicated, but works.
https://learn.microsoft.com/en-us/windows-hardware/drivers/d...
Nothing else in computing is like this. We just cannot help ourselves & each other in most realms of computing: we must be content with what we are given, as it is.
In almost all probability the linux system either doesn't have a GPU capable of running this high pixel clock or the cable/connector can't handle it. I'd love to know what the Mac & windows machines do; do they run 60Hz too or are they pushing all 144Hz here successfully? This seems very likely to be a cable issue, one I don't expect windows nor Mac deal with particularly excellently.