Comment # 17 on bug 58659 from Jerome Glisse

You also need step 12 of and please add :

printk(KERN_INFO "TITITOTOTUTUPOPO\n");

to

radeon_device.c line 992 after DRM_INFO("initializing ke ....

And when testing to make sure you are using the patched module dmesg | grep
TITITOTO

should tell you if it's the case.