Created attachment 116951 [details] dmesg log for 3.12.2 I upgraded from Linux 3.11.10 to 3.12.2, but the monitor went blank when the radeon driver loaded. According to the dmesg log: [ 1.993793] radeon 0000:02:00.0: No connectors reported connected with modes [ 1.993795] [drm] Cannot find any crtc or sizes - going 1024x768 The full log is attached. The system behaves properly when reverting to 3.11.10. I have a HD4890 / RV790 PCIE graphics card. Booting with radeon.aspm=0 or radeon.dpm=0 does not help.
Created attachment 116961 [details] Successful boot with 3.11.10 For reference, here is the dmesg log for a successful boot with 3.11.10.
Do you have radeon.hw_i2c=1 set somewhere? If so, it should be fixed by this commit: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=fae009d15a44e5f1d938340facf4b8bc7dc69a09
Created attachment 117291 [details] dmesg output when radeon.hw_i2c=0 I do have hw_i2c=1 in my /etc/modprobe.d/local.conf file, but the patch does not help. However, I am able to boot when I add radeon.hw_i2c=0 to the grub command line. dmesg output is attached.
Created attachment 117321 [details] possible fix Does the attached patch help?
Created attachment 117331 [details] dmesg output with 2nd patch applied No, the additional patch did not help.
Created attachment 117461 [details] possible fix Does this patch work any better?
Created attachment 117501 [details] dmesg output from 3.12.3 + 3rd patch I have just updated a second system from 3.11.10 to 3.12.3. This new system also experienced this bug, and the 3rd patch fixes it :-). I will test the 3rd patch on the other system next.
Created attachment 117511 [details] dmesg output from 3.12.3 + 3rd patch; original system The 3rd patch allows my original system to boot 3.12.3 as well. dmesg output is attached.