(In reply to comment #32)
> (In reply to comment #31)
> > (In reply to comment #30)
> > > 
> > >   I've set each register values from fglrx-console.data and call xinit.
> > > Lockup again, nothing changes.
> > 
> > Does the patch in comment 29 fix the issue for you?  That patch is upstream
> > now and should be in most stable kernels as well.
> 
>   To the pity, no. I've tested Linux 3.12 with the patch already applied and
> it changes nothing. My chip is:
> 
> $ lspci | grep 'VGA'
> 00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI]
> Sumo [Radeon HD 6480G]
> 
>   Is it really a SUMO2 chip or I should open a new bug?

What's the numeric pci id (lspci -nn)?  You should also see a line in the dmesg
output like this:
[    1.758014] [drm] initializing kernel modesetting (SUMO 0x1002:0x9640
0x1458:0xD000).

It will say SUMO or SUMO2 depending on which one you have.