From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Kozlowski Subject: Re: [PATCH v2] ARM: dts: Add missing CPU frequencies for Exynos5422/5800 Date: Thu, 5 Jan 2017 21:40:59 +0200 Message-ID: <20170105194059.bwpotpv3zjtvg5oz@kozik-lap> References: <10512254.nyUcL0zgTP@amdc3058> <20161229141707.qjrtjz7dik6a7l5s@kozik-lap> <2c85559a-dc12-610b-c842-c89d078e1c2a@osg.samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <2c85559a-dc12-610b-c842-c89d078e1c2a@osg.samsung.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Javier Martinez Canillas Cc: Mark Rutland , "devicetree@vger.kernel.org" , Thomas Abraham , Bartlomiej Zolnierkiewicz , Ben Gamari , "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" , Doug Anderson , Krzysztof Kozlowski , Russell King , linux-samsung-soc , Rob Herring , Kukjin Kim , Arjun K V , Andreas Faerber , "linux-arm-kernel@lists.infradead.org" List-Id: linux-pm@vger.kernel.org On Wed, Jan 04, 2017 at 08:57:47PM -0300, Javier Martinez Canillas wrote: > Hello Doug, > > On 01/04/2017 06:05 PM, Doug Anderson wrote: > > Hi, > > > > On Thu, Dec 29, 2016 at 6:17 AM, Krzysztof Kozlowski wrote: > >> On Thu, Dec 15, 2016 at 04:54:30PM -0800, Doug Anderson wrote: > >>>> Index: b/arch/arm/boot/dts/exynos5800.dtsi > >>>> =================================================================== > >>>> --- a/arch/arm/boot/dts/exynos5800.dtsi 2016-12-15 12:43:54.365955950 +0100 > >>>> +++ b/arch/arm/boot/dts/exynos5800.dtsi 2016-12-15 12:43:54.361955949 +0100 > >>>> @@ -24,6 +24,16 @@ > >>>> }; > >>>> > >>>> &cluster_a15_opp_table { > >>>> + opp@2000000000 { > >>>> + opp-hz = /bits/ 64 <2000000000>; > >>>> + opp-microvolt = <1250000>; > >>>> + clock-latency-ns = <140000>; > >>>> + }; > >>>> + opp@1900000000 { > >>>> + opp-hz = /bits/ 64 <1900000000>; > >>>> + opp-microvolt = <1250000>; > >>>> + clock-latency-ns = <140000>; > >>>> + }; > >>> > >>> I don't think the voltages you listed are high enough for all peach pi > >>> boards for A15 at 1.9 GHz and 2.0 GHz, at least based on the research > >>> I did. See my response to v1. > >> > >> I wanted to apply this but saw this remaining issue. Javier tested it > >> on Peach Pi so is this concern still valid? > > > > I'm not sure. It's been years since I did anything with exynos, so I > > won't stand in the way if everyone else agrees that this patch is > > good, but I will point out that testing on a single Peach Pi board is > > not really enough given the massive difference in voltage needed > > between the highest ASV group and the lowest (a whopping 112.5 mV from > > looking in the Chrome OS source tree). > > > > I agree. That's why answered that I wasn't able to find regressions on the > Peach Pi I've access to, but I couldn't provide a Reviewed-by tag since it > wasn't clear to me that the values were safe for any Exynos5420/5422/5800. The value of 1.250 V seems to be covering only half of ASV values for 2.0 GHz so indeed it might be insufficient for some of the chips. Unfortunately... Best regards, Krzysztof