Thanks for the input. I suspect the 24 inch screen worked normally because it was detected as 1920x1080 and 1080p and 720p resolutions work fine on every screen I’ve tried. It’s when I try other resolutions that things don’t work 100%. And when I set the 7 inch screen to either 1280x720 or 1920x1080 then things are fine. I can try setting it to a different resolution on the 24 inch screen and see if the bar appears there.
The 7 inch screen’s preferred resolution is 1024x600 at 60Hz. The manual for the screen has the following settings it suggests adding to the config.txt file for Raspberry Pi:
hdmi_force_hotplug=1
max_usb_current=1
hdmi_group=2
hdmi_mode=1
hdmi_mode=87
hdmi_cvt 1024 600 60 6 0 0 0
hdmi_drive=1
I’m not sure how to apply those settings to Ubuntu or Debian on the Radxa Zero though. I tried following the directions on https://wiki.radxa.com/Zero/hardware/display but that didn’t make any difference. After following those instructions I get the following output from xrandr:
rock@radxa-zero:~$ xrandr
Screen 0: minimum 320 x 200, current 1024 x 600, maximum 3840 x 2160
HDMI-1 connected primary 1024x600+0+0 (normal left inverted right x axis y axis) 255mm x 255mm
1024x600_60.00 59.85*+
1024x600 60.04 +
1920x1080 60.00
1600x900 60.00
1360x768 59.95
1280x720 60.00
I don’t know why it detects the default 1024x600 as 60.04 hertz and the new one (which I ran through the cvt command as 1024 600 60) as 59.85. I now suspect the frequency is the issue. The other three resolutions, which all show 60.00 as the refresh rate, work fine. I have to figure out a way to get that 59.85 to be 60. Do you know how to do that?