From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030555AbbJ3Kou (ORCPT ); Fri, 30 Oct 2015 06:44:50 -0400 Received: from mail-wm0-f41.google.com ([74.125.82.41]:34497 "EHLO mail-wm0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758636AbbJ3Kot (ORCPT ); Fri, 30 Oct 2015 06:44:49 -0400 Subject: Re: [PATCH] clocksource: dw_apb_timer_of: support timer-based delay To: Jisheng Zhang , tglx@linutronix.de References: <1446193659-1698-1-git-send-email-jszhang@marvell.com> Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org From: Daniel Lezcano Message-ID: <56334A1E.7060709@linaro.org> Date: Fri, 30 Oct 2015 11:44:46 +0100 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <1446193659-1698-1-git-send-email-jszhang@marvell.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/30/2015 09:27 AM, Jisheng Zhang wrote: > Implement an ARM delay timer to be used for udelay(). This allows us to > skip the delay loop calibration at boot on Marvell BG2, BG2Q, BG2CD > platforms. And after this patch, udelay() will be unaffected by CPU > frequency changes. > > Signed-off-by: Jisheng Zhang > --- > drivers/clocksource/Kconfig | 10 ++++++++++ > drivers/clocksource/dw_apb_timer_of.c | 16 ++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig > index a7726db..7b081805 100644 > --- a/drivers/clocksource/Kconfig > +++ b/drivers/clocksource/Kconfig > @@ -29,6 +29,16 @@ config DW_APB_TIMER_OF > select DW_APB_TIMER > select CLKSRC_OF > > +config DW_APB_TIMER_BASED_DELAY > + bool "DW APB timer based delay" > + depends on ARM && DW_APB_TIMER_OF > + default n > + help > + This option enables support for using the DW APB timer to > + implement timer-based delay. It is useful for skiping the > + delay loop calibration at boot on some platforms. And the > + udelay() will be unaffected by CPU frequency changes. > + Why do you want it to be optional ? -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog