With mainline git kernel build from yesterday (3.11.0-rc1+ #7 SMP Wed Jul 17
11:34:34 EDT) I see resume takes longer and the below is printed in system log
-

[ 7647.285017] sd 0:0:0:0: [sda] Starting disk
[ 7647.374821] [drm:atom_op_jump] *ERROR* atombios stuck in loop for more than
5secs aborting
[ 7647.374822] [drm:atom_execute_table_locked] *ERROR* atombios stuck executing
CD3E (len 55, WS 0, PS 0) @ 0xCD61

I think this started after DPM commits. Prior kernels don't show this error.

Hardware is 

lspci |grep VGA
01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Turks
PRO [Radeon HD 7570]