from http://bugs.debian.org/613918 : "current video-radeon driver in unstable [1:6.14.0-1] gave me a very blocky and tiled login screen [...] Problems disappeared when I changed "DefaultDepth 16" to 24." to which KiBi replied: "you shouldn't be using depth 16, it's broken in various ways, and kind of unsupported" But man 4 radeon still advertises "Full support for 8-, 15-, 16- and 24-bit pixel depths", and http://www.x.org/wiki/radeon does not list lacking <24-bit support as a known issue. Can anyone confirm the current state of 16-bit support, and bring the code and documentation in line?
It should work, although it doesn't get tested as often as depth 24 on newer asics. Can you bisect?
I could probably perform a bisection if needed, yes, but I'm not looking forward to it; I suspect that bisecting only the -video-radeon driver will not be enough, because of the ABI bump between xserver 1.7.7 and 1.9.4. But if you could provide some pointers to the correct upstream trees/branches, I'll see what I can do. Anyway, I've found some more time to try different things out, and it seems that things are not all dire: 16-bit mode works as expected if I start in single-screen and then use xrandr to re-enable dual-screen mode. I've also encountered two possible bugs with xrandr, but I have been able to reproduce both on 24-bit as well, so they're not the cause. I'll list them anyway: - xrandr CRTC assign seems iffy. When moving from clone mode to dual-display mode, both displays are not reassigned to separate CRTCs. I'll open a new bug for this - xrandr --verbose still lists the displays as Clones, even after succesfully enabling dual-display mode. Probably a cosmetic issue, I'll open a new bug if you want me to Maybe the issue is simply that I'm using the wrong xorg.conf entries, I'll attach it and list the relevant entries here: Section "Monitor" [...] Option "Rotate" "left" Option "Position" "1280 -896" Section "Screen" [...] SubSection "Display" Virtual 2360 1920
Created attachment 43555 [details] current xorg.conf
(In reply to comment #2) > - xrandr CRTC assign seems iffy. bug 34481
(In reply to comment #5) > from http://bugs.debian.org/613918 : > "current video-radeon driver in unstable [1:6.14.0-1] gave me a very blocky and > tiled login screen [...] Problems disappeared when I changed "DefaultDepth 16" > to 24." Isn't this bug 33929? In particular, doesn't Option "ColorTiling" "off" work around it? > to which KiBi replied: "you shouldn't be using depth 16, it's broken in various > ways, and kind of unsupported" Not true.
(In reply to comment #5) > Isn't this bug 33929? In particular, doesn't Option "ColorTiling" "off" work > around it? Thanks for the pointer. Yes, disabling colortiling fixes the issue: aschuring@neminis:~$ egrep Tiling\|Depth /var/log/Xorg.0.log [ 2552.677] (**) RADEON(0): Depth 16, (--) framebuffer bpp 16 [ 2552.677] (**) RADEON(0): Option "ColorTiling" "false" [ 2552.677] (II) RADEON(0): KMS Color Tiling: disabled *** This bug has been marked as a duplicate of bug 33929 ***
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