(In reply to comment #9)
> Completely powering down and removing the battery between boots does not
> help. I also tried 3.12 without success.
> 
> What's bothering me is that booting and not using X works. Is there any way
> I could disable UVD support and just keep the nice KMS'ed VTs?

Remove the UVD firmware from your system and initrd or patch the driver to not
enable UVD:

diff --git a/drivers/gpu/drm/radeon/radeon_uvd.c
b/drivers/gpu/drm/radeon/radeon_uvd.c
index 373d088..7177dbc 100644
--- a/drivers/gpu/drm/radeon/radeon_uvd.c
+++ b/drivers/gpu/drm/radeon/radeon_uvd.c
@@ -60,6 +60,8 @@ int radeon_uvd_init(struct radeon_device *rdev)
        const char *fw_name;
        int i, r;

+       return -EINVAL;
+
        INIT_DELAYED_WORK(&rdev->uvd.idle_work, radeon_uvd_idle_work_handler);

        switch (rdev->family) {