Quick update on the display issue.
I had seen this bug report, but my panel’s issue seemed different. A complete failure of the display, not 1/2 a display.
@minute’s comment here peaked my interest. I thought I had tried this by hacking the firmware’s call to “turn_som_power_on” to call the reset even on warm boot. Since that didn’t work I assumed it wasn’t the issue. But looking into the call stack, that function isn’t invoked on warm boot.
I hadn’t thought about wiring the reset into the bootloader. After some research into why a reset was needed on the Huai Zhi (V2) panel, I decided to try it in barebox and the rk3588s. I happen to be hacking around in barebox anyway, enabling the rk3588s. I’ve been able to get the firmware and barebox chatting over SPI and the reset now runs on every boot, warm or cold.
So far, the results are positive. The display seems to be working without any issue, and without any patches to the driver. That part is a bit confusing, but it’s not bad 
. I’ll update u-boot so that the same reset can be asserted on warm/cold boot for the A311D and i.MX SoCs.
To be clear, this doesn’t mean we shouldn’t still go the 2 driver route. This bootloader update simply ensures that when we split up the Linux driver, the Huai Zhi panel functions correctly.