From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH 2/2] arm64: dts: mt8173: add timer node To: Yingjoe Chen References: <1442369095-1094-1-git-send-email-yingjoe.chen@mediatek.com> <1442369095-1094-2-git-send-email-yingjoe.chen@mediatek.com> <55FAC570.8040307@arm.com> <1442501816.4784.3.camel@mtksdaap41> <55FAE69C.2000906@arm.com> <1443710016.22188.10.camel@mtksdaap41> Cc: Sudeep Holla , Matthias Brugger , Daniel Lezcano , Thomas Gleixner , Stephen Boyd , Michael Turquette , James Liao , "devicetree@vger.kernel.org" , Arnd Bergmann , Catalin Marinas , "linux-kernel@vger.kernel.org" , Rob Herring , "linux-mediatek@lists.infradead.org" , Sascha Hauer , Olof Johansson , "srv_heupstream@mediatek.com" , "linux-arm-kernel@lists.infradead.org" , Daniel Kurtz , "linux-clk@vger.kernel.org" , Eddie Huang From: Sudeep Holla Message-ID: <560D5227.8050600@arm.com> Date: Thu, 1 Oct 2015 16:32:55 +0100 MIME-Version: 1.0 In-Reply-To: <1443710016.22188.10.camel@mtksdaap41> Content-Type: text/plain; charset=utf-8; format=flowed List-ID: On 01/10/15 15:33, Yingjoe Chen wrote: > On Thu, 2015-09-17 at 17:13 +0100, Sudeep Holla wrote: >> [...] >> >> I think your are confusing the system counter with arch timers. System >> counter is always-on, but the arch timers(logic implementing timers >> comparators) might not be off when the processor is powered down. >> >> I think you need this timer and are using it for low power idle states >> in which case you will use this as a clock event and not clock source. >> It will be used as a hardware broadcast event source. >> >> There's no call to sched_clock_register in mtk_timer.c, so it can't be >> the sched clock, so you need to fix the commit log. > > Hi Sudeep, > > Sorry for late reply. > > For sched_clock_register, please see > http://lists.infradead.org/pipermail/linux-mediatek/2015-July/001547.html > which was accepted in > https://git.linaro.org/people/daniel.lezcano/linux.git/shortlog/refs/heads/clockevents/4.4 > The commit message makes no sense to me. The counters should continue to work as long as they are in always-on domain. Only timers are lost when you enter deeper idle states. So I agree with using MTK timer as broadcast timer/eventsource. You still didn't answer what's the need to use MTK timer as sched clocksource ? Regards, Sudeep