Comment 71 for bug 1034002

I'm not sure if I have the same issue. In particular, I could not find this error in my dmesg:
..
[drm:radeon_acpi_init] *ERROR* Cannot find a backlight controller
..

But I do have the issue that my laptop does not wake up fully (the screen is black).

There is some noise starts in the notebook and led indicators start blinking, but the screen does not turn ON.

I know, there are many possible reasons, but it worked with Catalyst, so, I think it has to be connected to video driver (dri, kms, xf86-video-ati, whatever..).

$ lspci | grep VGA
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] BeaverCreek [Radeon HD 6520G]
02:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Seymour [Radeon HD 6400M/7400M Series]

$ uname -a
Linux pilat-book 3.11.1-2-ARCH #1 SMP PREEMPT Sun Sep 22 19:45:00 CEST 2013 x86_64 GNU/Linux

I use radeon.dpm=1 in the kernel options;

Here's the bug-report to Archlinux tracker, but they suggested to file the bug here:
https://bugs.archlinux.org/task/37078