From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH] implement pm_ops.valid for everybody Date: Sat, 24 Mar 2007 21:04:31 +0100 Message-ID: <200703242104.33123.rjw@sisk.pl> References: <200703221344.l2MDi2Q9007989@olwen.urbana.css.mot.com> <200703231443.19536.rjw@sisk.pl> <17924.38452.751960.134885@cargo.ozlabs.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <17924.38452.751960.134885@cargo.ozlabs.ibm.com> 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: Paul Mackerras Cc: alexey.y.starikovskiy@intel.com, dirk.behme@de.bosch.com, johannes@sipsolutions.net, pavel@ucw.cz, linux-pm@lists.linux-foundation.org, nico@cam.org, ben@simtec.co.uk, g.liakhovetski@gmx.de List-Id: linux-pm@vger.kernel.org On Saturday, 24 March 2007 04:08, Paul Mackerras wrote: > Rafael J. Wysocki writes: > = > > > You said that if the hardware doesn't support a "turn CPU off" mode, = then > > > 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 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. > = > My old powerbook 3400 has a "sleep" mode where the CPU is in sleep > mode, consuming very little power (and I suspect its clock is switched > off), the RAM is kept refreshed, most of the peripherals are switched > off (except that the video chip keeps its register settings), and > wakeup is under the control of the PMU (power management unit). > = > My G4 powerbook has a "sleep" mode where the CPU is switched off, the > RAM is kept refreshed, most of the peripherals including the video > chip are switched off, and wakeup is under the control of the PMU. > = > As far as a user is concerned, both machines are doing the same thing > - they're asleep. Tell me why we should draw a distinction at a > user-visible level between what these machines are doing, when there > is no user-visible difference in behaviour? What I have in mind is the level at which we pass some argument (eg. PMSG_SUSPEND) to a driver's .suspend() routine and this argument should depend on the low-power state we want to enter and the meaning of it for the driver should be exatly known. Greetings, Rafael