Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752644AbbHCJD4 (ORCPT ); Mon, 3 Aug 2015 05:03:56 -0400 Received: from dd34104.kasserver.com ([85.13.151.79]:50182 "EHLO dd34104.kasserver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751705AbbHCJDy (ORCPT ); Mon, 3 Aug 2015 05:03:54 -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: References: <1438543386-7253-1-git-send-email-public_timo.s@silentcreek.de> 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: wens@csie.org, julian.calaby@gmail.com Cc: 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, maxime.ripard@free-electrons.com, 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: <20150803090352.621CC6C80865@dd34104.kasserver.com> Date: Mon, 3 Aug 2015 11:03:52 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1225 Lines: 30 Hi again, 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. However, Stefan Monnier (added to CC) mentioned in an earlier discussion that the savings for the lowest opp are rather small and thus the benefit of the 144MHz opp would be questionable. Unfortunately, I don't have measurement equipment precise enough to test this myself and haven't found a way to read power consumption internally via the PMU in mainline yet. 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/