Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932701AbWAGIdg (ORCPT ); Sat, 7 Jan 2006 03:33:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932702AbWAGIdg (ORCPT ); Sat, 7 Jan 2006 03:33:36 -0500 Received: from HELIOUS.MIT.EDU ([18.248.3.87]:33437 "EHLO neo.rr.com") by vger.kernel.org with ESMTP id S932701AbWAGIdf (ORCPT ); Sat, 7 Jan 2006 03:33:35 -0500 Date: Sat, 7 Jan 2006 03:36:02 -0500 From: Adam Belay To: Pavel Machek Cc: Patrick Mochel , Andrew Morton , Linux-pm mailing list , kernel list Subject: Re: [linux-pm] [patch] pm: fix runtime powermanagement's /sys interface Message-ID: <20060107083602.GE3184@neo.rr.com> Mail-Followup-To: Adam Belay , Pavel Machek , Patrick Mochel , Andrew Morton , Linux-pm mailing list , kernel list References: <20051227213439.GA1884@elf.ucw.cz> <20051227220533.GA1914@elf.ucw.cz> <20060104213405.GC1761@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20060104213405.GC1761@elf.ucw.cz> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1859 Lines: 44 On Wed, Jan 04, 2006 at 10:34:05PM +0100, Pavel Machek wrote: > On ?t 27-12-05 20:22:04, Patrick Mochel wrote: > We want _common_ values, anyway. So, we do not want "D0", "D1", "D2", > "D3hot" in PCI cases. We probably want "on", "D1", "D2", "suspend", > and I'm not sure about those "D1" and "D2" parts. Userspace should not > have to know about details, it will mostly use "on"/"suspend" anyway. > > > > One day, when we find device that needs it, we may want to add more > > > states. I don't know about such device currently. > > > > There are many devices already do - there are PCI, PCI-X, PCI Express, > > ACPI devices, etc that do. But, you simply cannot create a single > > decent > > I asked for an example. Look at the ACPI spec, it has several examples... 1.) most sound cards have more than two states. (once again latency over power savings trade offs) 2.) many PCI devices with wake support use different D-levels depending on wake settings 3.) PCI buses have B0, B1, B2, and B3 (and yes these are very different from D-states). This catagory also includes cardbus bridges. 4.) IDE hard drives and other storage media have "sleep", "suspend", etc. 5.) SATA controllers have more states than just "on" and "off". Also these states are independent of the PCI d-states. 6.) many video cards implement D1 and D2 as you've already seen. This is often more a matter of "we only know how to restore from such and such states" 7.) Many processors support of wealth of different power states This list is not exhaustive. Also, embedded platforms probably have serveral more examples. Thanks, Adam - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/