From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: usb suspend (was Re: So, what's the status on the recent patches here?) Date: Sun, 27 Aug 2006 01:34:08 +0200 Message-ID: <20060826233408.GE2551@elf.ucw.cz> References: <20060825220320.GH9568@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.osdl.org Errors-To: linux-pm-bounces@lists.osdl.org To: Alan Stern Cc: linux-pm@lists.osdl.org List-Id: linux-pm@vger.kernel.org Hi! > > > The idea of the patches is that they will autosuspend a USB hub when = it > > > has no active (i.e., unsuspended) children, and autosuspending a root= hub > > > stops the USB controller from doing DMA. However, non-hub devices ar= e not > > > yet automatically suspended, so you will have to suspend the fingerpr= int > > > scanner by hand. > > = > > That is okay, I can do that. It saves 2 hours of battery life on my > > machine... > = > Come to think of it, you don't need the autosuspend patches to turn these = > devices off. You can do it right now with your existing kernel, although = > it's a little easier with -mm. (The reason is that -mm contains a = > development patch which ties a USB device's interfaces to the device = > itself; suspending the device will automatically suspend all its = > interfaces, and likewise resuming the device will automatically resume al= l = > its interfaces. With a vanilla kernel you must manually suspend the = > interfaces before you can suspend the device and manually resume them = > after resuming the device.) > = > Anyway, you can use the deprecated = > = > echo -n 2 >/sys/devices/.../power/state > = > mechanism to suspend all the USB interfaces, devices, and controllers you = > want -- provided you work your way up from the bottom of the device tree.= = > The autosuspend patch just makes it simpler, since it takes care of = > suspending and resuming all the hubs for you. Thanks! That works great and gets my power consumption into reasonable range.. plus allows fan to actually stop. Pavel -- = (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html