From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755691Ab0IMUCS (ORCPT ); Mon, 13 Sep 2010 16:02:18 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:34549 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754959Ab0IMUCQ (ORCPT ); Mon, 13 Sep 2010 16:02:16 -0400 Date: Mon, 13 Sep 2010 16:02:16 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Oliver Neukum cc: Jiri Slaby , Dmitry Torokhov , , linux-pm , Linux kernel mailing list , Subject: Re: [linux-pm] wacom + runtime PM = AA deadlock In-Reply-To: <201009132105.38204.oliver@neukum.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 13 Sep 2010, Oliver Neukum wrote: > Am Montag, 13. September 2010, 17:17:54 schrieb Alan Stern: > > On Mon, 13 Sep 2010, Oliver Neukum wrote: > > > > > 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Stern Subject: Re: [linux-pm] wacom + runtime PM = AA deadlock Date: Mon, 13 Sep 2010 16:02:16 -0400 (EDT) Message-ID: References: <201009132105.38204.oliver@neukum.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Return-path: In-Reply-To: <201009132105.38204.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org To: Oliver Neukum Cc: Jiri Slaby , Dmitry Torokhov , pingc@wacom.com, linux-pm , Linux kernel mailing list , linux-input@vger.kernel.org List-Id: linux-input@vger.kernel.org On Mon, 13 Sep 2010, Oliver Neukum wrote: > Am Montag, 13. September 2010, 17:17:54 schrieb Alan Stern: > > On Mon, 13 Sep 2010, Oliver Neukum wrote: > > > > > 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