From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brownell Subject: Re: [PATCH] implement pm_ops.valid for everybody Date: Fri, 23 Mar 2007 10:57:15 -0700 Message-ID: <200703231057.16539.david-b@pacbell.net> References: <200703221344.l2MDi2Q9007989@olwen.urbana.css.mot.com> <200703221655.17693.david-b@pacbell.net> <200703231443.19536.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <200703231443.19536.rjw@sisk.pl> 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: "Rafael J. Wysocki" Cc: alexey.y.starikovskiy@intel.com, ben@simtec.co.uk, dirk.behme@de.bosch.com, pavel@ucw.cz, linux-pm@lists.linux-foundation.org, johannes@sipsolutions.net, nico@cam.org, g.liakhovetski@gmx.de List-Id: linux-pm@vger.kernel.org On Friday 23 March 2007 6:43 am, Rafael J. Wysocki wrote: > On Friday, 23 March 2007 00:55, David Brownell wrote: > > You said that if the hardware doesn't support a "turn CPU off" mode, th= en > > you'd define that as being incapable of implementing suspend-to-RAM. > = > That's _if_ the suspend-to-RAM is defined as the state in which the CPU > is off, which I _think_ would be a reasonable definition. = I disagree. > I don't mean the = > platforms incapable of doing this should be restricted from entering any > system-wide low-power states, but perhaps we can call these states > differently. Well, we have ** ONLY TWO LABELS TO APPLY ** and you're saying that one of them should be restricted to systems where the CPU can go into an "off" state. = > > That's a restriction ... a very arbitrary one. > > = > > = > > ... > > My point is that _if_ we use lables like "standby", "STR", "STD", etc., That is, the strings in /sys/power/state. That's a given for now... > then they shouldn't mean different things on different platforms. = Unreasonable. The platforms are different. And moreover the specifics DO NOT MATTER to userspace. Plus, they can differ even on two x86 systems: different D-states, different wakeup events. So nobody has any valid expectation that STR on one box has exactly the same behavior on a different box. And if users are trained to expect anything, it's that platforms will differ in those details. > So, either = > we don't use labels at all, or we should know what they mean regardless > of what platform we're talking about. That's a false choice, when you "mean" anything more than fairly broad behavioral expectations: STR saves more power than "standby", and transitions to/from STR take more time than to/from "standby". - Dave