Created attachment 141422 [details]
Contents of /proc/cpuinfo on successful boot
My Fedora 28 desktop stopped booting up cleanly after switching to the 4.17 kernel where amdgpu.dc became the default... the system seems to be working (e.g when installing updates, it automatically reboots once done), but the screen goes black immediately after grub loads the kernel, and it remains that way indefinitely. Passing "amdgpu.dc=0" on the kernel command line resolves the problem.
The active graphics card is an AMD RX-470, the CPU is an AMD A10-7850k (with unused onboard graphics).
This was logged on the RedHat bugzilla, but after receiving no response in over a month, I've opted to log it here instead. Here's the link to the downstream bug:
I've re-attached the same files provided there – the output of lspci, dmesg, and /proc/cpuinfo for a successful boot – but if you need anything else to track this down, let me know.
Created attachment 141423 [details]
Output of lspci on successful boot
Created attachment 141424 [details]
Output of dmesg on successful boot
If you can provide a dmesg log for your black screen boot that would help.
Created attachment 141459 [details]
Output of journalctl -k on failed boot
Created attachment 141460 [details]
Output of journalctl -k on successful boot
Ok, I've added the output of "journalctl -k -b" (the current, successful boot) and "journalctl -k -b -1" (a failed boot a few minutes previously).
Can you try booting with amdgpu.dc=0 in your kernel boot parameters?
(In reply to Nicholas Kazlauskas from comment #7)
> Can you try booting with amdgpu.dc=0 in your kernel boot parameters?
As noted in the original bug report, "passing "amdgpu.dc=0" on the kernel command line resolves the problem." The "successful boot" logs I've provided were all captured under that setting, since the system is unusable without it.
I *suspect* the system is booting fine apart from the graphics, because when Fedora reboots to apply updates, it does so successfully before powering off as expected – I just can't see anything on the screen.
Just to add - Same happens to me with an R9 380 graphics card since amdgpu.dc was enabled. I am using my monitor through the vga port (with an dvi to vga adapter on my gpu). Passing "amdgpu.dc=0" also resolves the problem for me. Is there any debug that I should provide that may help?
Created attachment 141483 [details]
output of journalctl on failed boot with amdgpu.dc=1 amdgpu.dc_log=1
Is there any update on this, any more information I can provide to help get this fixed? I can confirm it's still occurring on the 4.19.5-200 kernel currently included in Fedora 28...