Created attachment 115416 [details] dmesg output In Debian Jessie, I get a black screen booting with KMS enabled. The backlight remains lit, but the screen displays as black. It happens on boot up about when these lines appear: [ 16.797096] [drm] Initialized drm 1.1.0 20060810 [ 18.117763] [drm] radeon kernel modesetting enabled. From then on I can log in blind, and I'm running pbbuttonsd so the brightness keys can dim or brighten the screen, but it always remains black. Switching to a console also gives me a black screen. Adding the kernel parameters video=offb:off radeon.modeset=1 radeon.agpmode=-1 changed nothing. This isn't a new problem, I've had it in previous Debian releases, but I hope someone might take a crack at this. Right now the only workaround is to disable KMS and work with a very slow desktop (and no mplayer or vlc fullscreen upscaling). This is on an G3 iBook (M8603LL/A - PowerBook4,3 - A1007) Thanks, Dan
Created attachment 115417 [details] output of cat /var/Xorg.0.log
Created attachment 115418 [details] output of lspci -vvv
Oddly, screen mirroring works perfectly. The external monitor shows my desktop as intended, but the iBook's screen remains bleak, I mean, black. I also generated a xorg.conf file to disable acceleration, but it didn't help.
This line in dmesg indicates a problem with the dot clock: [drm:drm_calc_timestamping_constants] *ERROR* crtc 14: Can't calculate constants, dotclock = 0!
The issue: [...] [drm:drm_calc_timestamping_constants] *ERROR* crtc 14: Can't calculate constants, dotclock = 0! [...] can also be seen here: https://bugs.freedesktop.org/show_bug.cgi?id=91428
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