Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932604AbbHDIve (ORCPT ); Tue, 4 Aug 2015 04:51:34 -0400 Received: from dd34104.kasserver.com ([85.13.151.79]:37831 "EHLO dd34104.kasserver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932360AbbHDIvc (ORCPT ); Tue, 4 Aug 2015 04:51:32 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-SenderIP: 153.96.32.62 User-Agent: ALL-INKL Webmail 2.11 In-Reply-To: <20150803093420.GC2564@lukather> References: <1438543386-7253-1-git-send-email-public_timo.s@silentcreek.de> <20150803090352.621CC6C80865@dd34104.kasserver.com><20150803093420.GC2564@lukather> Subject: Re: [linux-sunxi] [PATCH] ARM: dts: sunxi: Raise minimum CPU voltage for sun7i-a20 to a level all boards can supply From: "Timo Sigurdsson" To: maxime.ripard@free-electrons.com Cc: wens@csie.org, julian.calaby@gmail.com, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, linux@arm.linux.org.uk, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com, monnier@iro.umontreal.ca Message-Id: <20150804085130.602FA6C83EF9@dd34104.kasserver.com> Date: Tue, 4 Aug 2015 10:51:30 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1767 Lines: 40 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/