I recently bought a second-hand Dasung Paperlike Color Revolutionary monitor, and was hoping to be able to use it with the Reform.
However, I can’t seem to get the display to work with the Reform (with A311D SoM), and therefore wanted to ask if by chance anyone has tried this and succeeded.
I of course first tested the Reform’s HDMI output with a regular 1920x1080@60Hz monitor, and that works following the instructions here, but wlr-randr seems to be very relucant to enable the 3200x1800@33.033033Hz native resolution/refresh-rate of the display… (“Failed to apply configuration”)
I also tried passing the respective modeline (obtained from the monitor edid via edid-decode -X) to swaymsg output HDMI-A-1 modeline, but while there was no error message on the command line, the screen remained blank (or rather, on the test pattern that the Dasung screens show if there is no signal).
For reference, this is the modeline I tried to use: swaymsg output HDMI-A-1 modeline 220.000 3200 3400 3432 3600 1800 1813 1823 1850 +HSync +VSync
I know that the screen itself is working, as I can use it on both, my desktop (Linux, running sway too), and the work PC I got from the company (Windows).
So, to repeat my question:
Has by chance anyone tried the same combination of SoM and Monitor? If yes, did you get it working? If yes, how?
Hi! That’s an exciting display and I would love to see it work, but I’m not sure if that’s easy to do with the A311D. My guess is it would work well with the RK3588 if that could be an option for you. Otherwise I would first check if the A311D can currently output 4K modes. AFAIK at some point there has to be some extra “scrambling” in HDMI to make the higher-pixelclock modes work. Although 220MHz doesn’t seem that high. With dmesg -n 7 set first, do you see any further output in dmesg -w when trying your modeline?
The only output I get with dmesg -n 7 when running the command swaymsg output eDP-1 disable; swaymsg output HDMI-A-1 enable; swaymsg output HDMI-A-1 modeline 220.000 3200 3400 3432 3600 1800 1813 1823 1850 +HSync +VSync; is:
The latter is not reliably reproducible, but happens occasionally.
It also seems to be the case (but I need to try this once more) that trying to set the relatively high-resolution modeline causes the HDMI output to get stuck in a bad state. I don’t know if that happens always, or only after the vblank timeout has been hit, but when I tried a 1080p screen after trying to get the Paperlike Color running, I didn’t get any output until I rebooted once.
I have been thinking about upgrading the SoM to the RK3588 for some time already, and the hope to get this external screen working is another good reason to buy it. On the other hand, the A311D is still (just) fast enough for my needs, and since I run a custom kernel, the thought of having to go over the whole driver config again makes me a bit reluctant to switch SoM just yet…