From mboxrd@z Thu Jan 1 00:00:00 1970 From: albin.tonnerre@free-electrons.com (Albin Tonnerre) Date: Fri, 9 Oct 2009 12:53:30 +0200 Subject: [PATCH v2] Add cpuidle support for at91 In-Reply-To: <4AC35582.8000404@atmel.com> References: <1247680190-19674-1-git-send-email-albin.tonnerre@free-electrons.com> <200908111200.58866.marc.pignat@hevs.ch> <20090812165700.GC4051@pc-ras4041.res.insa> <200908130858.47487.marc.pignat@hevs.ch> <20090813193241.GA5985@pc-ras4041.res.insa> <20090909151417.GA4014@pc-ras4041.res.insa> <4AC2168B.60903@atmel.com> <20090930123449.GB3238@laptop> <4AC35582.8000404@atmel.com> Message-ID: <20091009105330.GA2191@pc-ran3241.res.insa> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, 30 Sep 2009 14:56 +0200, Nicolas Ferre wrote : > Albin Tonnerre : > >> Just one precision: what is the difference, entering state0 with only > >> the current cpu_do_idle() that is activated by default ? > > > > Sorry, I don't get what you mean. Would you mind elaborating a bit? > > I guess that during idle time, even without the cpuidle infrastructure, > the SOC enters arch_idle() that calls cpu_do_idle(). > > So, now that I have your patch applied, I wonder what is the difference > between the old situation and the first state of the cpuidle table. > > In other words, only state "wait-for-interrupt *and* RAM self refresh" > brings some more power saving. Indeed, cpu_do_idle() that correspond to > the "WFI" state was already the way of dealing with idle cpu, even > without your patch. Am I correct ? Indeed, only the second mode brings us some gain. Regards, -- Albin Tonnerre, Free Electrons Kernel, drivers and embedded Linux development, consulting, training and support. http://free-electrons.com -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 835 bytes Desc: Digital signature URL: