image size too large for 10.2 " screen

[TheOldPresbyope]

@Facel 

Is there not a full version (e.g., with desktop) Raspberry Pi OS i(RaspiOS) image you can boot on this Allo USB Bridge?

True, RaspiOS has close to a pure debian root filesystem but it has its own kernel, drivers, and tweaks.

I assume you booted a full version of debian rather than a lite version---you do have a desktop displayed, right? I'm going to assume it's running either pure X11 or X11 under Wayland and not pure Wayland.

What does debian say the screen resolution is (width-in-pixels by heighth-in-pixels) when you say "the display is ok"?

For example:


- moOde 8.3.7 on a Pi3B+ driving an official 7" LCD touchscreen via DSI (bullseye release of underlying debian).

Code:

pi@home:~ $ DISPLAY=:0 xrandr
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 800 x 480, current 800 x 480, maximum 800 x 480
default connected 800x480+0+0 0mm x 0mm
  800x480        0.00*

- current RaspiOS on a PI400 driving my desktop monitor via HDMI (bookworm release of underlying debian)

Code:

kreed@pi400:~ $ DISPLAY=:0 xrandr
Screen 0: minimum 16 x 16, current 1920 x 1080, maximum 32767 x 32767
XWAYLAND4 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 510mm x 290mm
  1920x1080     59.96*+
  1440x1080     59.99  
  1400x1050     59.98  
  1280x1024     59.89  
  1280x960      59.94  
  1152x864      59.96  
  1024x768      59.92  
  800x600       59.86  
  640x480       59.38  
  320x240       59.52  
  1680x1050     59.95  
  1440x900      59.89  
  1280x800      59.81  
  720x480       59.71  
  640x400       59.95  
  320x200       58.96  
  1600x900      59.95  
  1368x768      59.88  
  1280x720      59.86  
  1024x576      59.90  
  864x486       59.92  
  720x400       59.55  
  640x350       59.77  

Extended Display Identification Data (EDID) is the metadata standard used by an HDMI interface in returning information about a connected display. That's how RaspiOS knows the resolutions of the desktop monitor I used in the above example.

RaspiOS can ignore this returned EDID information, substituting a set of EDID data of its own. If nothing else, we can try to fake it 'til we make it. with your touch screen display.

[aside]

We'll never know what the native resolution of your physical LCD panel is. You've got a blackbox HDMI (digiral) to VGA (analog) converter which is driving the VGA input port of the blackbox display interface which converts the VGA (analog) signals into the specific digital signals needed by the input lines of the physical LCD panel. By blackbox, I mean we have no idea what's inside.

[aside #2]

RaspiOS is transitioning to Wayland. For the time being we're ok, but in future moOde will be more dependent on Wayland, not X11. Different tricks may have to be played.

Ain't life grand?

Regards,
Kent