From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jim Gettys Subject: Re: [RFC] dynamic device power management proposal Date: Thu, 22 Mar 2007 07:56:46 -0400 Message-ID: <1174564606.4935.6.camel@localhost> References: <200703220042.20471.lenb@kernel.org> Reply-To: jg@laptop.org Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <200703220042.20471.lenb@kernel.org> 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: Len Brown Cc: linux-pm@lists.linux-foundation.org, linux-pm List-Id: linux-pm@vger.kernel.org On Thu, 2007-03-22 at 00:42 -0400, Len Brown wrote: > Today on system suspend we suspend all devices. > Today on system resume, we resume all devices. > In the future we need to recognize that upon system suspend, > some devices are already suspended. > We need to remember that, so upon resume we can restove > them to their suspended state, rather than blindly resuming everything. On system suspend, we may not want to suspend all devices; we may need to leave certain devices alone, and only power down the host interface to them. Upon system resume, therefore, devices may also *not* need to be resumed; only the host interface to them powered up again. We have two devices in the OLPC machine in this class: our screen, and our wireless, both of which will often/usually be left on while the rest of the sysetm is suspended. - Jim -- = Jim Gettys One Laptop Per Child