Chromebox display port not functioning

Hi Guys,

I have an Asus Chromebox, the display port is connected to an LG Tv on HDMI2 to get 4k and HDMI goes to my receiver for 7.1 (which also goes to TV HDMI1), this worked perfectly on 10.0.x but I have recently updated to 11.0.0.1 and I get a black screen on the display port but I can get a screen via the HDMI port which goes through the receiver then TV.

I do not have the monitor option in Kodi settings display to pick the main screen, I am pretty sure it was there before. I do see the Chromeos developer screen and also the Libre splash screen on both ports when booting up (if I pick HDMI1 or 2 on TV)

if I unplug the HDMI and reboot I get a display on the display port.

I have googled and searched and only thing I can see is

LibreELEC:~ # dmesg | grep -e i915

[ 0.573975] i915 0000:00:02.0: vgaarb: deactivate vga console

[ 0.627299] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem

[ 0.628167] i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/kbl_dmc_ver1_04.bin (v1.4)

[ 1.753551] i915 0000:00:02.0: [drm] failed to retrieve link info, disabling eDP

[ 1.756670] i915 0000:00:02.0: [drm] [ENCODER:94:DDI B/PHY B] is disabled/in DSI mode with an ungated DDI clock, gate it

[ 1.756677] i915 0000:00:02.0: [drm] [ENCODER:120:DDI D/PHY D] is disabled/in DSI mode with an ungated DDI clock, gate it

[ 1.769267] [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 0

[ 2.400331] fbcon: i915drmfb (fb0) is primary device

[ 2.405271] i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device

[ 3.723908] i915 0000:00:02.0: [drm] *ERROR* [ENCODER:110:DDI C/PHY C][DPRX] Failed clock recovery 80 times, giving up!

[ 5.036292] i915 0000:00:02.0: [drm] *ERROR* [ENCODER:110:DDI C/PHY C][DPRX] Failed clock recovery 80 times, giving up!

But even if I disconnect the HDMI and DP works I get the same error in the log though so it might not be related..

They do say don't fix what isn't broke.. but I can't help myself, any thoughts before I just go back to the older version?

Some extra stuff.

Both show as connected

LibreELEC:~/.kodi/temp # cat /sys/class/drm/card0-DP-2/status

connected

LibreELEC:~/.kodi/temp # cat /sys/class/drm/card0-HDMI-A-1/status

connected

Seems to be EDID data on both if I

LibreELEC:~/.kodi/temp # edid-decode /sys/class/drm/card0-DP-2/edid

Sees the correct thing

Display Product Name: 'LG TV'

and

LibreELEC:~/.kodi/temp # edid-decode /sys/class/drm/card0-HDMI-A-1/edid

Display Product Name: 'TX-SR876'

I also downgraded and now have the "monitor" option in settings/display. Giving me the choices of DP2 and HDMI1.

Happy to put whatever version on and do any tests required Just wanted to make sure it wasn't something else that happened during upgrade

Thanks Chewitt, I have seen your answers all over the forum.

I had figured out about the GBM vs Xorg changeover after reading some more but I didn't realise that was the limitation. So no way to use the DP port for display and HDMI for audio only? I just tried unplugging TV from AVR hoping that would use the DP for video but no luck..

HDR would be good to have though with the OLED.. Looks like this kind of device would do it? HDMI Audio Extractor that is definitely an easy way to do it, AVR was purchased just as 3D was becoming a thing so won't do 3D or 4K with the HDMI it supports so that's why direct to TV for display. Not likely to upgrade anytime soon.

Assuming this is a general Linux thing for HDR support so using some other flavour and Kodi doesn't help? I think I already know the answer.

So I can

Go back to LE10 and stop looking for updates (4k, no HDR, 7.1)

Go to LE11 and get an extractor (4k, HDR, 7.1)

Go to LE11 legacy and no HDR (4k, no HDR, 7.1)

I think HDR for a ~$100 once off fee is a good deal, I loved repurposing the old chromebox as dual boot and having this work, previously had an old I3 NUC and couldn't do 4k so this was a nice change. I really only use it to play movies from a NAS.

Well the device I got technically works but I found the chromebox 3 doesn't support using it.. from the Wiki

Kabylake Chromeboxes were released in the Spring of 2018, and feature a few notable improvements over the previous Haswell/Broadwell models (which are effectively identical). The Kabylake SoC provides a nice speed bump, but more importantly the GPU features full 10-bit HEVC/VP9 decoding, as well as 4Kp60 output (via USB-C DisplayPort alt-mode).

Unfortunately, the GPU in the Kabylake SoC still doesn't natively support HDMI 2.0 output. This means that 4Kp60 output still requires the use of a DisplayPort to HDMI 2.0 adapter (via the USB-C port), and thus a LSPCON (level shifter/protocol converter). The use of a LSPCON means that HD audio bitstreaming almost certainly won't work (due to driver limitations), so one must choose between using the HDMI 1.4 output with HD audio, or the USB-C output with 4K output.

So 4k via usbc but it won't send the audio this way.. I just get the HDMI on AVR flickering and never syncing..

I'll go back to the legacy image for now, and wait until there is a cheapish box that will do 4k and HDR with the device or natively do audio out a different port?..

How do I mark as resolved because it isn't really a bug..