Hmm, this is probably based on not-yet-merged usbhid autosuspend patchset, 
right?

Yes, that's right. I looked at the wrong tree.
 

Now, you are right that hiddev_open() doesn't handle error condition from 
usbhid_open(), and that should be fixed. But that doesn't seem to be 
addressed by your patch at all ... ?

Yes I am looking at hiddev currently and have found several errors.
I'll make patches for the appropriate trees.

	Regards
		Oliver