Ultrawide native resolution 2560x1080_60 not accepted by nvidia-driver-470 x Quadro P620

I just installed Xubuntu LTS release 20.04, Focal Fossa.

I have four monitors model LG 25UM58-P (LED 25" Ultrawide Full HD) connected to one single NVIDIA GPU Quadro P620 (GP107GL-A) using 4 HDMI to mDP adapters.

I successfully achieved 2560x1080 resolution using the Modesetting driver with this hardware setup. This makes me sure that although there may be considerations about the adapters used in this hardware setup, this hardware configuration can achieve 2560x1080.

The problem I’m facing now is that I’m trying to achieve such a resolution using the NVIDIA driver because it’s an accelerated driver.

For every error message displayed be NVIDIA driver I added a ModeValidation value in my xorg.conf file. For example:

  • NoMaxPClkCheck because driver displayed a message “Mode is rejected: PixelClock (185.6 MHz) too high for Display Device (Max: 165.0 MHz).
  • AllowNonEdidModes because driver displayed a message “Mode is rejected: Only EDID-provided modes are allowed on LG Electronics LG ULTRAWIDE (DP-1) (continuous frequency modes not allowed).
  • Added many values because of the message “Mode is rejected: Unable to construct hardware-specific mode timings”. - I removed these values to simplify this bug report

But there’s a message I just can’t solve: “GPU extended capability check failed
Thought NoExtendedGpuCapabilitiesCheck should eliminate this message, but it seems like having no effect

Is there any known BUG about NoExtendedGpuCapabilitiesCheck ? Is it being ignored because it conflicts with another parameter ?

How can I say to my NVIDIA driver that it should trust me and just apply the Modeline 2560x1080 from my monitor EDID (the driver detected it, but rejected it), or the one I informed in the Monitor Section of xorg.conf?

I can’t believe I’ll have to abandon the driver written by my Quadro P620 card manufacturer and go back to the Modesetting driver.

NVIDIA Bug Report:
nvidia-bug-report.log.gz (512.0 KB)