I have been trying, without success, to make current version of DietPi build for Odroid C1 run with two screens:
- Kodi in X should go to HDMI output (TV), using /dev/fb0
- my python program should go to FBTFT device, which is LCD attached to GPIO, like original Odroid’s touch screen, using /dev/fb2
The LCD works without a problem when I manage to direct the output to it.
Now, this setup did work on my previous distro, which was Odrobian, using simple dual-head xorg.conf.
Although, I had to change Kodi and Mali drivers from Xorg to fb versions, and that did the trick, with only small hiccup: after starting the program on /dev/fb2, primary screen on /dev/fb0 (HDMI output) would go blank, but after 5-10s it would go back and continue happily to work in parallel with the one on TFT LCD.
Now, with DietPi, it does not happen - the moment I start my python program on /dev/fb2, primary HDMI output goes blank and stays that way. If I stop my python program, Kodi/X return to HDMI output.
In Xorg logs I have seen the complaint like “VGA arbiter not found in kernel” saying something like “I can’t run two different video cards” (if I understood correctly) and X spits error on the TFT LCD section in xorg.conf and skips past it (something like “screen 1 not configured”).
It is interesting that even if I do not use dual-head xorg.conf setup, but keep the original single-head (with output only over HDMI /dev/fb0) I still can get output on /dev/fb2, but same behaviour for /dev/fb0 - it goes blank while anything is shown on /dev/fb2.
At the same time, xorg log file shows something like “leaving VT” when HDMI switches off, and “returning to VT” when it get back on.
So I tried xorg.conf options that might be related to VT switching, and got nowhere.
I have looked in kernel doc’s and as far as I can see, VGA arbiter is in use only for normal VGA outputs and just on some platforms - ARM not being one.
So, how come it worked on Odrobian?
I tried fiddling with con2fbmap and fbset, but it got me nowhere as well.
My question is - is this even possible without recompiling Kodi (and Xorg?) to work on FB?
Should I go back to Odrobian, even though it is not maintained anymore?
Is there another way, maybe through USB port, using some “translator” chip? What are my options, in general…?
I know this is a long and messy question, but I’m in a messy situation and I have to get this working somehow…