4k @ 60hz output on Librem 13v2 (via USB C or HDMI)


#1

Just wondering if anyone has had any success in getting 4k @ 60hz output with their Librem 13v2? I have tried 4 different ‘high speed’ HDMI cables and have been unsuccessful on 2 different 4K @ 60hz capable displays.

Additionally, has anyone tried to use a USB C > HDMI converter, USB C > MiniDP or USB C > Displayport converter to achieve this?

(running stock PureOS)


#2

bump

Can anyone confirm what the maximum resolution I should be getting over the HDMI port at 60hz?


#3

HDMI ver 1.4 only supports 4k @ 30hz.


#4

Thanks for that.

Do you know if there are any USB C or USB 3 > HDMI adaptors that are compatible with the Librem to pump out 4k @ 60hz?


#5

Just tried a USB C to HDMI adaptor:

www.comsol.com.au/Products-by-Category/HDMI-Video-Cables/COCMHFAD

Claims it doesn’t need drivers, but it doesn’t do anything, just blank screen. Long shot, but anything I need to do to perhaps initialise the hardware?


#6

No, our USB-C does not support video, this is planned in the future.


USB-c to VGA adapter on Librem 15v3?
#7

For folks who have gotten 4k out the hdmi port on the Librem 13v2 did you have to do anything in particular? I tried plugging in a 4k monitor but the OS only lets me select up to 1920x1080.


#8

I plugged the HDMI out directly into the port labeled ‘HDMI 2.0’ on a 4k monitor and the max res I got to choose was 1080p :frowning:

Tried multiple cables, including ones that I knew could do 4k on other devices on the same monitor.


#9

I can get 2560 x 1400 out of the HDMI port on my 13v2 in Xorg mode by manually adding Modelines with xrandr. I have not been able to get these higher resolutions in wayland following these instructions. Upon boot there is an error that the firmware was not loaded. I have also tried setting options to the drm_kms_helper with a modprobe.d file:

$ cat /etc/modprobe.d/drm-kms-helper.conf 
options drm_kms_helper edid_firmware=HDMI-A-1:edid/2560x1440.bin

but either way it seems I am getting the error

[drm:drm_load_edid_firmware [drm_kms_helper]] *ERROR* Requesting EDID firmware "edid/2560x1440.bin" failed (err=-2)

#10

This is being tracked in https://tracker.pureos.net/T298.

From my research it is not a PureOS-specific issue and is most likely an issue with the kernel and the i915 module in the 4.x series with some Skylake hardware (I’ve seen similar reports for some Dell XPS laptops).

I tried a number of different distribution Live USB disks and was only able to get full resolution out of a 4k display if I went back to an old Ubuntu 14.04 live USB disk that ran a 3.x kernel.

We are continuing to research the issue to provide a solution. Keep an eye on the ticket for updates.


#11

Like hazybluedot, I was able to add a mode in Xorg (but not Wayland). I wrote up the steps to do it and make it permanent in the official PureOS ticket on this issue.


#12

I have just tried it with my Librem 13v2 with a DELL U3818DW via HDMI and Ubuntu 18.04:

There is no 4K output possible ATM due to the bug, the max. solution offered in the display settings for the external 4K-monitor is FullHD (1920 x 1080).

So you have to apply the workaround by adding modlines. The allowed values may be limited by the GPU performance (Intel 520) so 4K could be possible only with 30 Hz… (to be verified)