Kernel Bug Tracker – Bug 39672
[r280] Black screen on PPC with digital monitor on radeon / Cannot find any crtc or sizes
Last modified: 2011-08-08 08:40:21 UTC
Created attachment 66132 [details]
syslog from system without video output
Testing Kernel 3.0.0 (rc6 from Debian experimental) I encountered a problem with (DVI) display detection - the screen goes blank when trying to activate KMS. From syslog:
[drm:radeon_add_legacy_connector] *ERROR* DVI: Failed to assign ddc bus! Check dmesg for i2c errors.
[drm] DDC: no ddc bus - possible BIOS bug - please report to firstname.lastname@example.org
No connectors reported connected with modes
[drm] Cannot find any crtc or sizes - going 1024x768
To me this looks quite similar to #23222.
With a VGA monitor the screen does not go blank, but I still don't get the login window in KDM (?).
I'm using Ubuntu 11.04 and with a self-compiled 2.6.39-rc7 kernel I have working KMS (even though direct rendering does not work, as reported on https://bugs.freedesktop.org/show_bug.cgi?id=37169 ).
Created attachment 66382 [details]
This patch should fix the i2c setup.
Great, now I'm running Linux 3.0. :-)
And the best thing: it looks like there's also progress regarding the aforementioned bug I reported on freedesktop.org - I'll have to investigate further. This is what glxinfo reports (instead of 'software renderer'):
"OpenGL renderer string: Mesa DRI R200 (RV280 5962) 20090101 PowerPC/Altivec TCL DRI2"
Please close this bug if the patch hits Linus tree.
A patch referencing this bug report has been merged in Linux v3.1-rc1:
Author: Alex Deucher <email@example.com>
Date: Sat Jul 23 18:02:04 2011 +0000
drm/radeon/kms: fix i2c map for rv250/280