Black Screen when in libreelec, but display works on bios screen

    So when I boot up my mini PC when connected to LG smart tv, I get video signal, and it shows the initial bios screen. Then when you would normally get the libreelec boot screen and Kodi boot screen, then Kodi menu, all of that part it's black screen.

    Via

    tail /sys/class/drm/*/status

    I am able to see both the HDMI port on my box, and it shows connected for the port the TV is plugged in to. So the connection is good. No idea why this is happening. Maybe a libreelec/Kodi setting?

    Any help figuring out what's up would be appreciated! Thank you

    Quote from chewitt
    Code
    video=HDMI-A-1:1920x1080M@60

    If the box is connected to the HDMI-A-1 connector append this ^ to boot params in syslinux.cfg and see if forcing the initial DRM output to 1080@60 helps. Adjust as needed for whichever connector is connected. You want to run the GUI at 1080p anyway (see: https://wiki.libreelec.tv/configuration/4k-hdr).

    Hi, so I tried to do that in /flash/syslinux.cfg but I don't have permission to write even as root. Just says read-only file system, so I cannot modify the files!

    Quote from CoolPenguin42

    Hi, so I tried to do that in /flash/syslinux.cfg but I don't have permission to write even as root. Just says read-only file system, so I cannot modify the files!

    Code
    mount -o remount,rw /flash
nano /flash/syslinux.cfg
mount -o remount,ro /flash
reboot
    Quote from Da Flex
    Code
    mount -o remount,rw /flash
nano /flash/syslinux.cfg
mount -o remount,ro /flash
reboot

    Great, that worked! And now it does display which is perfect. However a few questions. I can't seem to tell from the docs, but all my media is native 4k. Is this downscaling to 1080p then having tv upscale? Or will this auto output it at 4k when it should and then just have the GUI ONLY at 1080p? Thanks!

    Quote from CoolPenguin42

    Great, that worked! And now it does display which is perfect. However a few questions. I can't seem to tell from the docs, but all my media is native 4k. Is this downscaling to 1080p then having tv upscale? Or will this auto output it at 4k when it should and then just have the GUI ONLY at 1080p? Thanks!

    Ah so I forgot to turn on the change refresh rate thing in player settings, so that auto selected. But then black screen again.


    HOWEVER, a bunch of googling yielded results. The HDMI Ultra HD Deep Color setting was my issue. With that turned on no 4k would display. With it off, it works. Any idea what the setting is and why it killed the video out? And is there a solution to make it work with it on (since the setting seems cool)

    Enabling deep colour changes HDMI properties advertised by the TV on the HDMI port to include 12-bit 4:2:2 and I'd guess that the display chain cannot handle the additional bandwidth required for 4K60 and thus sync is lost. Disabling deep colour forces 8/10-bit 4:2:0 output and allows things to work. The most common issue with 4K60 video is the HDMI cable not being able to sustain higher bandwidths required (esp. when combined with HD audio). Do you have 4K60 certified cables?

    There is very little real-world media in 4K60 format (most is under 4K30) and almost nothing in 12-bit (only 10-bit) so if the cable is not the issue, disabling deep colour on the TV or leaving the video= change in syslinux.cfg and never using 4k50/59.94/60 modes (where the issue will probably reappear) are both options. The video= change only forces the initial connector state to 1080@60, it does not prevent Kodi from detecting and using 4K modes with the whitelist later.