Hey, sorry to hijack this post but I am having a similar problem and I'm trying to get any info that can help me figure this out.
I was initially able to see an N64 rom play on the screen perfectly fine. Then, while it was on, I plugged it into an HDMI and it seemed like it detected it but did not send the image to the TV so I shut it down and tried turning it back on while being plugged into the TV. This time the retropie menu was mirrored both on the screen and the TV. When I selected the N64 emulator the entire image and sound were now present only on the TV (the screen remained black for this).
But now, every time I run the emulator it defaults to sending the image to the HDMI. I can plug it into the TV while the screen is black and I'll see and hear the rom playing on the TV. I hadn't changed the emulator options prior to this, so unfortunately I don't know if there were different values prior to this.
These are the options I see enabled now:
System: n64
Emulator: mupen64plus-auto
Video mode: 1024x768 @ 60 Hz 4:3, clock: 65MHz progressive
ROM: Legend of Zelda, The Ocarina of Time
After entering the emulator I see an error in the daemon.log saying that there was a DMA channel collision:
retropie fbcpFilledNoSleep[380]: DMA channel collision! DMA channel 1 was expected to be assigned to our peripheral 7, but something else has assigned it to peripheral 17!
From my very limited understanding, I think it initially tried to use the screen through SPI (peripheral 7) but something else assigned it to HDMI (peripheral 17).
Is there an easy way to revert whatever configuration was assigned when I plugged it into the TV?
Attached is the daemon.log after the emulator is started. (Edit: might not have permissions to attach files yet, here's the file:
https://filebin.net/tj4z5diw0ua1kvtc)
PS: I have the latest CM3 image installed (Freeplay_CM3_19110701) with the FastNoSleepFilled LCD driver selected.
Thanks in advance!