From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752014AbdA3KWP (ORCPT ); Mon, 30 Jan 2017 05:22:15 -0500 Received: from mail-wm0-f47.google.com ([74.125.82.47]:38169 "EHLO mail-wm0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751884AbdA3KWM (ORCPT ); Mon, 30 Jan 2017 05:22:12 -0500 Date: Mon, 30 Jan 2017 11:21:27 +0100 From: Daniel Lezcano To: Alexander Kochetkov Cc: Heiko Stuebner , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, Thomas Gleixner , Mark Rutland , Rob Herring , Russell King , Caesar Wang , Huang Tao Subject: Re: [PATCH v5 4/8] ARM: dts: rockchip: disable arm-global-timer for rk3188 Message-ID: <20170130102127.GB2206@mai> References: <1485260203-14216-1-git-send-email-al.kochet@gmail.com> <1485260203-14216-5-git-send-email-al.kochet@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1485260203-14216-5-git-send-email-al.kochet@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 24, 2017 at 03:16:39PM +0300, Alexander Kochetkov wrote: > clocksource and shed_clock provided by arm-global-timer is quite > unstable, because their rate depends on cpu frequency. > So disable arm-global-timer and use clocksource and sched_clock > from rockchip_timer. > It is impossible get stable clocksource having rockchip_timer and > arm-global-timer enabled at the same time. Because arm-global-timer > looks like a better candidate for the kernel: it has higher > frequency and rating. > > Disabling arm-global-timer doesn't leave kernel without > clockevents as there is another clockevent provider (smp-twd). Hi Alexander, sorry, I will rewrite the description because of the grammatical errors. I don't want to give you the feeling I'm lecturing you, my English is not perfect but it will be simpler to give the full descr with the typos fixed. " The clocksource and the sched_clock provided by the arm_global_timer are quite unstable because their rates depend on the cpu frequency. On the other side, the arm_global_timer has a higher rating than the rockchip_timer, it will be selected by default by the time framework while we want to use the stable rockchip clocksource. Let's disable the arm_global_timer in order to have the rockchip clocksource selected by default. " This patch should go at the end of the patchset when the clocksource is implemented in the rockchip_timer. > Signed-off-by: Alexander Kochetkov > Reviwed-by: Heiko Stübner > --- > arch/arm/boot/dts/rk3188.dtsi | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm/boot/dts/rk3188.dtsi b/arch/arm/boot/dts/rk3188.dtsi > index bcf8e03..f677130 100644 > --- a/arch/arm/boot/dts/rk3188.dtsi > +++ b/arch/arm/boot/dts/rk3188.dtsi > @@ -546,6 +546,7 @@ > > &global_timer { > interrupts = ; > + status = "disabled"; > }; > > &local_timer { > -- > 1.7.9.5 > -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog