Re: wacom + runtime PM = AA deadlock

On Mon, 13 Sep 2010, Oliver Neukum wrote:

Am Montag, 13. September 2010, 17:17:54 schrieb Alan Stern:

quoted

On Mon, 13 Sep 2010, Oliver Neukum wrote:

quoted

PM in this driver looks broken. Please try this.

In short you want to drop the PM reference and depend on remote
wakeup and busy marking for this driver. Currently it gets a reference
on every open() but never drops it.

For locking you depend on the PM core's internal lock. You simply
make sure you have a PM reference during open() and close()

Is there any point in resuming the device during close() just in order
to kill the interrupt URB?  It seems counterproductive -- if the device 
had been suspended then there wouldn't be any interrupt URB to kill in 
the first place.

Suppose the device does not support remote wakeup. It would never
be autosuspended while it is open, but simply resetting the flag
would never reach the PM layer.

Whoops, that's right.  I didn't see the assignment to 
needs_remote_wakeup.

How come wacom_open doesn't check to see if wacom->open is already set?

Alan Stern