From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [RFC] dynamic device power management proposal Date: Thu, 22 Mar 2007 12:58:32 -0700 Message-ID: <200703221258.33306.david-b@pacbell.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: linux-pm@lists.linux-foundation.org List-Id: linux-pm@vger.kernel.org On Monday 19 March 2007 8:44 am, Alan Stern wrote: > On Mon, 19 Mar 2007, Shaohua Li wrote: > = > > ... > > Basically we need device driver support, a kernel framework and a policy > > (determine when to change a device=E2=80=99s power state). > = > A lot of development along these lines has already been going on in the = > USB subsystem. It isn't complete yet, but a lot of the ideas you raise = > have already been implemented. ISTR pointing out a few years ago that USB makes a good testbed for such things, in technical terms ... it's got the "complete problem" wrapped up in one more-or-less modern subsystem. So making it do PM well has been an object lesson in how the Linux PM infrastructure works -- or, too often, doesn't. The most troublesome spot being that ACPI interferes on PCs, so we can't yet do stuff like put EHCI/OHCI/UHCI controllers into PCI_D2 at runtime and rely on remote wakeup. But embedded Linux systems make it easy to work with saner frameworks; on those systems you can see even more of the pieces working well together. :) - Dave