https://bugzilla.kernel.org/show_bug.cgi?id=199621 Matthew Trescott (matthewtrescott@xxxxxxxxx) changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |matthewtrescott@xxxxxxxxx --- Comment #6 from Matthew Trescott (matthewtrescott@xxxxxxxxx) --- Created attachment 276935 --> https://bugzilla.kernel.org/attachment.cgi?id=276935&action=edit strace log of xorg when I ran the command that fixes this problem I have a 21.5-inch Mid-2010 iMac with the same Mobility Radeon HD 4670 GPU. It also exhibits this problem (the solution in #100301 doesn't work either); however I can temporarily fix it by running the following command (I had to type it blindly because it won't work over SSH): xrandr -d :0 --output eDP-1 --crtc 1 After which everything works well, including backlight control via /sys/class/backlight/radeon_bl0/brightness. The fix does not persist across reboots or even across log-out/log-in cycles (I guess the handoff between Xorg and radeondrmfb triggers some sort of reset and the problem comes back). I'm on kernel 4.17.2 (Arch Linux). I'm no Linux graphics expert, but I did capture an strace of all the ioctl calls from Xorg during while running the above command as well as monitoring sysfs with inotifywait. Nothing relevant happened in sysfs, but there were a few interesting system calls from when I ran the command that I've attached. -- You are receiving this mail because: You are watching the assignee of the bug. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
