Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752569AbbHCCiM (ORCPT ); Sun, 2 Aug 2015 22:38:12 -0400 Received: from smtp.csie.ntu.edu.tw ([140.112.30.61]:34074 "EHLO smtp.csie.ntu.edu.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750924AbbHCCiC (ORCPT ); Sun, 2 Aug 2015 22:38:02 -0400 MIME-Version: 1.0 In-Reply-To: References: <1438543386-7253-1-git-send-email-public_timo.s@silentcreek.de> From: Chen-Yu Tsai Date: Mon, 3 Aug 2015 10:37:35 +0800 Message-ID: Subject: Re: [linux-sunxi] [PATCH] ARM: dts: sunxi: Raise minimum CPU voltage for sun7i-a20 to a level all boards can supply To: Julian Calaby Cc: public_timo.s@silentcreek.de, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , Maxime Ripard , devicetree , "Mailing List, Arm" , "linux-kernel@vger.kernel.org" , linux-sunxi , Chen-Yu Tsai Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1521 Lines: 40 Hi, On Mon, Aug 3, 2015 at 7:35 AM, Julian Calaby wrote: > Hi Timo, > > On Mon, Aug 3, 2015 at 5:23 AM, Timo Sigurdsson > wrote: >> sun7i-a20.dtsi contains an cpufreq operating point at 0.9 volts. Most A20 boards >> (or all?), however, do not allow the voltage to go below 1.0V. Thus, raise the >> voltage for the lowest operating point to 1.0V so all boards can actually use >> it. > > Surely it wouldn't be added here if some could supply 0.9v. On the side, the original OPPs in the FEX files are actually frequency/voltage ranges, and not just points. Mainlines OPPv2 will support these, along with turbo frequencies. Furthermore, the FEX files also have fields that limit the minimum and maximum frequencies. > Is the code that uses this smart enough to sensibly switch between two > operating points with the same frequency and different voltages? If > so, maybe just add a 144MHz @ 1.0v operating point? You could try. Though I really don't see much to gain here. > (Alternatively, would it make sense to modify the code that uses this > to use frequencies with voltages specified that are lower than can be > supplied with the lowest voltage it can?) I think that's a bit harder to get accepted. ChenYu -- 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/