Hello, I’m new to the community so apologies if this isn’t the right place for this!
I recently bought a Cubie A7Z but am getting corrupted video when outputting to a 1872x1404@60 sink, despite fully-trained link and correct MSA.
My environment is as follows:
| Image | Radxa Debian 11 (bullseye) KDE R6 |
|---|---|
| Kernel | 5.15.147-21-a733 |
| DP driver | CONFIG_AW_DRM_TRILINEAR_EDP14=y (sunxi_drm_edp.c + trilinear_dp14.c) |
| Output | USB-C 3.1 port, DP Alt Mode, pin assignment C (4-lane), orientation NORMAL |
| Sink | DASUNG Paperlike 103 — 1872x1404@60, 193 MHz, DP 1.2 |
(The same monitor works correctly from two other hosts (laptop with USB-C DP Alt Mode, and another over an active HDMI→USB-C adapter), so the sink works as expected with other devices)
The panel receives a stream and does report a video signal, but renders a corrupted fine-grained grey noise that is independent of displayed content (identical when trying to output the desktop, a solid-white frame or solid-black frame).
The corruption persists when the framebuffer is taken out of the path entirely.
Driving the TCON’s own built-in pattern generator — sunxi_tcon_show_pattern() via /sys/devices/virtual/edp/edp/attr/colorbar, verified as actually applied by reading back tcon_tv_src_ctl (0x5731040) = 5 (all-ones / solid white) — still produces the same noise. Patterns 4 (all-zero), 1 (colour bars) and 3 behave identically.
So the fault likely lies downstream of the TCON’s pixel source and upstream of the sink, in the TCON → Trilinear DP-TX path. I’ll put more details in a github report.
Has anyone else encountered issues like this before? I’d be happy to do further testing with my DASUNG display, but there are lots of things I’ve tried already, so am quite disappointed as DP Alt Mode compatibility was a big part of why I bought this device. If anyone has any suggestions or advice that would be most appreciated.
Thanks,
Joel 