Created attachment 278653 [details] kernel 4.18.7 dmesg Kernel 4.17 is working but the last 2 versions of 4.18.* will not register my HDMI TV connected to an RX 480. I have a Dell LCD on DP and an LG TV on HDMI. If I unplug the DP display after grub screen the computer will have no display.
Created attachment 278655 [details] Working kernel 4.17 dmesg
For the time being, maybe amdgpu.dc=0 on the kernel command line can serve as a workaround.
Thank you Michel. That fixes it.
Do you only see this problem occur before you start an X session? It might help if you could post a log from 4.18 with drm.debug=6 included in your boot parameters.
Created attachment 278677 [details] Kernel 4.18 with drm.debug=6
(In reply to Nicholas Kazlauskas from comment #4) > Do you only see this problem occur before you start an X session? > > It might help if you could post a log from 4.18 with drm.debug=6 included in > your boot parameters. Im running Fedora 28 so it wayland. When I remove the quiet from the kernel line the HDMI display works so a few seconds until the GUI for the boot drive encryption displays only on the second display only. I attached the file with drm.debug=6
It doesn't look like your log buffer was large enough to hold the full log. A log with drm.debug=4 might have enough information to work off of. The other option is reposting the drm.debug=6 log with a large log buffer size in the kernel config.
Hay the machine can do a large buffer. How do I enable that. I saw it cut off at 30 seconds. Its ryzen 1700, 16G ram and many hd's
It should be the CONFIG_LOG_BUF_SHIFT option. For example, CONFIG_LOG_BUF_SHIFT=21.
Created attachment 278683 [details] kernel 4.18 drm.debug=4
Created attachment 278687 [details] Kernel 4.18 drm.debug=6
(In reply to Nicholas Kazlauskas from comment #9) > It should be the CONFIG_LOG_BUF_SHIFT option. For example, > CONFIG_LOG_BUF_SHIFT=21. Updated the file.