From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Timo Sigurdsson" Subject: Re: [PATCH] ARM: dts: sunxi: Raise minimum CPU voltage for sun7i-a20 to a level all boards can supply Date: Tue, 4 Aug 2015 10:51:30 +0200 (CEST) Message-ID: <20150804085130.602FA6C83EF9@dd34104.kasserver.com> References: <1438543386-7253-1-git-send-email-public_timo.s@silentcreek.de> <20150803090352.621CC6C80865@dd34104.kasserver.com><20150803093420.GC2564@lukather> Reply-To: public_timo.s-fWgRPtSzPNU3WX+qO2AYSQ@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <20150803093420.GC2564@lukather> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org Cc: wens-jdAy2FN1RRM@public.gmane.org, julian.calaby-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org, galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, monnier-CRDzTM1onBSWkKpYnGOUKg@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Maxime, Maxime Ripard schrieb am 03.08.2015 11:34: > On Mon, Aug 03, 2015 at 11:03:52AM +0200, Timo Sigurdsson wrote: >> Julian Calaby schrieb am 03.08.2015 06:22: >> > My only real objection here is are there boards that can go down to >> > 0.9v and if so, won't this change make them less power efficient in >> > the almost-idle case? And are those power savings enough to justify >> > not accepting this patch? >> >> It will probably make those boards less power efficient, yes. On the >> other hand, boards that have their CPU regulator set to min. 1.0V might >> also draw more power because the lowest frequency is not available, >> even though the savings due to frequency are likely to be lower than >> the savings due to voltage. > > Guys, isn't this whole discussion a bit moot? We're not doing any kind > of power management but cpufreq, so maybe there's a lot more to do > before we actually can have these kind of arguments? > > Plus this OPP has never been used anyway, so this patch is not going > to increase the power consumption either. You are right. When I wrote that, I was under the impression that the Olinuxino Lime 2 board at least used this setting since it has has a cpu regulator defined to go as low as 0.7V. But now I checked again and see the regulator is not referenced in the cpu node, so I guess cpufreq doesn't use it. So, this discussion was really hypothetical and more importantly, as you mentioned, it's an out-of-spec opp that shouldn't be supported anyway. Thanks, Timo