From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: nokia 770 [was Re: community PM requirements/issues and PowerOP] Date: Wed, 13 Dec 2006 22:58:31 +0100 Message-ID: <20061213215831.GG12253@elf.ucw.cz> References: <20060914101704.GA17820@elf.ucw.cz> <457FEE17.8080806@gmail.com> <20061213210359.GC11843@elf.ucw.cz> <200612131332.58606.david-b@pacbell.net> <45807708.3090607@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: <45807708.3090607@gmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.osdl.org Errors-To: linux-pm-bounces@lists.osdl.org To: "Eugeny S. Mints" Cc: linux-pm@lists.osdl.org, matthew.a.locke@comcast.net, scott.preece@motorola.com, Amit Kucheria List-Id: linux-pm@vger.kernel.org On Thu 2006-12-14 00:56:24, Eugeny S. Mints wrote: > David Brownell wrote: > >On Wednesday 13 December 2006 1:03 pm, Pavel Machek wrote: > >>On Wed 2006-12-13 15:12:07, Eugeny S. Mints wrote: > >>>David Brownell wrote: > >>>>On Tuesday 19 September 2006 11:25 am, Pavel Machek wrote: > >>>>>Could you perhaps provide list of operating points for 770? It would > >>>>>help understanding a bit, I'd say. > >>>>If there was a followup here, I missed it ... > >>>> > >>>>ISTR that it doesn't use (formal) operating points, and that a lot of = > >>>>the > >>>>basic SOC power savings (vs powering off the display or wifi) come fr= om = > >>>>a > >>>>different kind of mechanism entirely. Namely, a combination of dynam= ic > >>>>tick with a modified system idle task, which enters one of the OMAP l= ow > >>>>power modes during those long periods between clock ticks or other ir= qs. > >>>> > >>>>That's one of the standard power saving schemes used on OMAP1 platfor= ms > >>>>with Linux. > >>>sample of reasonable operating points for OMAP1 platforms along with = > >>>appropriate patches may be found at = > >>>http://dynamicpower.sourceforge.net/dpm-omap.html > > > >That's the old DPM stuff not any of the newer proposals right? > > > >I thought the question was specifically what N770 used. > > > > > >>Okay... so you have system with 4 different cpu speeds. That should be > >>simple enough to get running using cpufreq, no need for complex > >>operating points patches. > > > >And OMAP1 does have cpufreq support. I believe that if I checked it out > >I'd find that it's used on N770, as a good way to kick in low voltage > >operation modes. > > > >... that's in addition to the reduced power idle, which didn't seem to > >fit into the DPM framework in any obvious way. > It fits. Omitting some details DPM allows to map/stick operating point to = > tasks. Mapping one of OMAP low power mode operating point to idle task do= es = > the job. That's what I call a hack. Take a look at acpi C1..C3 state on i386. They provide same functionality ("reduced power idle"), but they are implemented in reasonable way and already merged. Pavel -- = (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html