Radeon X200M device suspend problem

[Dmitriy Kryuk]

I have a laptop with a Radeon X200M card in it. I use Radeon DRM driver 
for graphics, and it makes the system hang with display off when trying 
to suspend (either to disk or to RAM). Using /sys/power/pm_test 
interface revealed that it freezes when suspending devices.

I have tried both Debian repository kernel 
(https://packages.debian.org/stable/linux-image-3.16.0-4-686-pae) and a 
custom-built vanilla 3.18.45 kernel with this driver both built-in and 
included as a module. The problem reproduces the same way. It stops to 
reproduce if I delete the module radeon.ko or otherwise prevent it from 
loading. The problem didn't appear before I started using DRM.

dmitriy at laptop:~$ dmesg | grep -i radeon
[   18.520307] [drm] radeon kernel modesetting enabled.
[   18.521610] radeon 0000:01:05.0: VRAM: 128M 0x0000000078000000 - 
0x000000007FFFFFFF (128M used)
[   18.521667] radeon 0000:01:05.0: GTT: 512M 0x0000000080000000 - 
0x000000009FFFFFFF
[   18.526251] [drm] radeon: 128M of VRAM memory ready
[   18.526303] [drm] radeon: 512M of GTT memory ready.
[   18.558510] [drm] radeon: 1 quad pipes, 1 z pipes initialized.
[   18.558685] radeon 0000:01:05.0: WB enabled
[   18.558739] radeon 0000:01:05.0: fence driver on ring 0 use gpu addr 
0x0000000080000000 and cpu addr 0xf48a6000
[   18.558896] radeon 0000:01:05.0: radeon: MSI limited to 32-bit
[   18.558983] [drm] radeon: irq initialized.
[   18.696262] [drm] radeon: ring at 0x0000000080001000
[   18.697892] [drm] Radeon Display Connectors
[   18.736547] radeon 0000:01:05.0: fb0: radeondrmfb frame buffer device
[   18.736601] radeon 0000:01:05.0: registered panic notifier
[   18.736660] [drm] Initialized radeon 2.40.0 20080528 for 0000:01:05.0 
on minor 0
dmitriy at laptop:~$ lspci | grep -i radeon
01:05.0 VGA compatible controller: Advanced Micro Devices, Inc. 
[AMD/ATI] RC410M [Mobility Radeon Xpress 200M]

dmitriy at laptop:~$ lsmod
Module                  Size  Used by
fbcon                  42796  71
bitblit                12545  1 fbcon
softcursor             12333  1 bitblit
tileblit               12517  1 fbcon
ath9k_htc              50765  0
radeon               1438969  2
ath9k_common           21530  1 ath9k_htc
ath9k_hw              369801  2 ath9k_common,ath9k_htc
ath                    21707  3 ath9k_common,ath9k_htc,ath9k_hw
cfbfillrect            12474  1 radeon
cfbimgblt              12335  1 radeon
cfbcopyarea            12334  1 radeon
i2c_algo_bit           12640  1 radeon
drm_kms_helper         71528  1 radeon
ttm                    67750  1 radeon
drm                   207864  5 ttm,drm_kms_helper,radeon

What additional information can I collect and how? What other kernel and 
driver versions can I try to see if the problem is already solved? What 
other ways can I help to solve the problem in?