Comment 62 for bug 1034002

I've the same issue on my HP4545s laptop (A4-4300M CPU).
At boot time I get
...
[drm:radeon_acpi_init] *ERROR* Cannot find a backlight controller
...
then the computer boots and works just fine (except the brightness control is @ /sys/class/backlight/radeon_bl0/brightness, commonly unrecognizable by the software) but after resuming I have totally black screen. I can still ssh to it: it resumes normally - the only thing that goes wrong is the screen remains off. (It goes off as soon as the resume process begins). Kernels 3.9.X still have the issue.
I'm not sure the absence of the ACPI-controllable brightness is relevant to the case.