suspend trouble

[coypu%SDF.ORG@localhost]

Hi, I've been trying to play with suspend on my laptop which has an ATI
RV770 (I think ATI Mobility HD5430).

Suspend & resume works once (most of the time, if I don't hit other
bugs), but not a second time.

I've also noted that with pcictl dump I saw some changed values:
Before suspend->After resume
Device Control Register: 0x0800->0x2810
Enable Relaxed Ordering: off->on
Max Read Request Size: 128->512 bytes

_ What are those changes? are they problematic?

drvctl -S radeon0 && sleep 1 && drvctl -R radeon0 always works.
Also, it does not change the pci conf values.

- How can I reproduce the same scenario as in suspend with drvctl?

I saw a few times:
DRM error in rv770_stop_dpm: Could not force DPM to low.

It seemed happier (I don't see this error now) after I added:

dev->switch_power_state = DRM_SWITCH_POWER_OFF;
(or ON)

before the call to radeon_suspend_kms in radeon_do_suspend in
/cvsroot/src/sys/external/bsd/drm2/radeon/radeon_pci.c

But still no dice, it will crash after second resume.

Ideas?