HDMI out is not working with HDMI to VGA converter with Raspberry Pi 4

HarryH · July 9, 2024, 7:49pm

I’m afraid you have to play a little with manual set the display resolution via cmdline.txt. The newer kernel versions are very sensitive to the EDID data. In combination with your VGA adapter, these could be missing or may be incomplete.
Within the case, the power is supplied via GPIO pins, not via the USB-C. That could cause a difference in timing while switching on.

Try to append this to the kernel line in the /boot/firmware/cmdline.txt
video=HDMI-A-1:1280x1024M@60D

github.com

raspberrypi/linux/blob/rpi-6.1.y/Documentation/fb/modedb.rst

=================================
modedb default video mode support
=================================


Currently all frame buffer device drivers have their own video mode databases,
which is a mess and a waste of resources. The main idea of modedb is to have

  - one routine to probe for video modes, which can be used by all frame buffer
    devices
  - one generic video mode database with a fair amount of standard videomodes
    (taken from XFree86)
  - the possibility to supply your own mode database for graphics hardware that
    needs non-standard modes, like amifb and Mac frame buffer drivers (which
    use macmodes.c)

When a frame buffer device receives a video= option it doesn't know, it should
consider that to be a video mode option. If no frame buffer device is specified
in a video= option, fbmem considers that to be a global video mode option.

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