i915 cannot detect display on 1060NG7 (Iris Graphics) since after linux4.19

Where is it happening:

• BMax B6 Power (Ice Lake i7-1060NG7)
• This machine is provided with a modified (illegal) Windows 11 and a custom graphics driver, most probably because the CPU does not use the correct pins for the integrated display.
• This machine has 2 HDMI ports (same issue on both obviously)
• No BIOS update is provided by BMAX (of course)

What is happening:

• With Linux 4.19, display is detected but I suffer many display artefacts (wrong gamma, blinking overlays).
• With Linux 5.0 and above (6.13 included), modesetting immediately switches the screen off.
• Using USB to connect to a screen works... but it's USB 3.0 (5 Gbps) and 1920x1080@30 is the best resolution that works (60Hz gives buffer underruns and signal loss for every updated frame).

I tried many kernel options to no avail. The only description I found that made sense is the behaviour with Generation 9 CPUs attached to an "unexpected" pin layout (TGP PCH); it was same behaviour and it was patched here: https://patchwork.freedesktop.org/patch/412664/

However, it seems that Gen 10 was overlooked but it can be used on a different pin-out too. I want this resolved since I'm not the only one to suffer from this.

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added Community platform: ICL labels

added feature: display/Other label

CC : @tejasu @jani @vsyrjala

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