Librem 14 / Mini v2: 2560x1440 displays on HDMI do not work in all configurations/resolutions
Similar issues have been reported on Librem 14 and Mini: when using 2x 2560x1440 displays, the display connected via HDMI does not work in all configurations or resolutions.
Reported on Librem 14:
- With both displays connected (using HDMI and USB-C), the HDMI display only works up to 2048x1152. Selecting a higher resolution results in no signal on the display.
- With only the HDMI display connected, the highest selectable resolution is 1024x768. It appears that the system fails to read EDID from the display.
Reported on Librem Mini v2:
- With both displays connected (HDMI, and using a passive DP-HDMI adapter on DP), selecting the DP-HDMI display as primary results in both displays working. Selecting the HDMI display as primary results in neither display working, both lose signal.
- Disconnecting the DP-HDMI display results in the HDMI display losing signal as well.
- Booting with only HDMI connected displays the SeaBIOS bootsplash, but then the display blacks out before reaching the disk decryption prompt.
In Librem 14, Mini v1, and Mini v2, the HDMI port is provided via a Parade PS175B (to support HDMI 2.0 resolutions, since the SoC natively only supports HDMI 1.4).
While the reports differ somewhat, I think the underlying issue is the same.