How to properly install Radeon drivers for Sid

[Mostafa Shahverdy <mostafa@mostafa.info>]

Hi everyone.

I have an ultra wide monitor that supports 2560x1080. 
While I have a Radeon 5450 graphic card, running Debian Sid, I only can get 1920x1080. 
I installed firmware-linux-nonfree to get it running. So why isn't my complete resolution listed?
Also I experience some glitches while watching videos.

I have to mention that I can't install the proprietary driver from AMD website because of the following error:

<code>
    make[1]: Entering directory '/usr/src/linux-headers-4.5.0-2-amd64'
      CC [M]  /lib/modules/fglrx/build_mod/2.6.x/firegl_public.o
    /lib/modules/fglrx/build_mod/2.6.x/firegl_public.c: In function ‘firegl_major_proc_read’:
    /lib/modules/fglrx/build_mod/2.6.x/firegl_public.c:634:9: error: void value not ignored as it ought to be
         len = seq_printf(m, "%d\n", major);
             ^
    /lib/modules/fglrx/build_mod/2.6.x/firegl_public.c: In function ‘KCL_fpu_save_init’:
    /lib/modules/fglrx/build_mod/2.6.x/firegl_public.c:6458:49: error: ‘XSTATE_FP’ undeclared (first use in this function)
           if (!(fpu->state.xsave.header.xfeatures & XSTATE_FP))
</code>

-- 
Regards,
Mostafa Shahverdy <http://www.mostafa.info/pgp>

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