From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754861Ab3GARzU (ORCPT ); Mon, 1 Jul 2013 13:55:20 -0400 Received: from www.linutronix.de ([62.245.132.108]:56478 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753207Ab3GARzS (ORCPT ); Mon, 1 Jul 2013 13:55:18 -0400 Date: Mon, 1 Jul 2013 19:55:15 +0200 (CEST) From: Thomas Gleixner To: Jonas Jensen cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, arm@kernel.org, john.stultz@linaro.org, u.kleine-koenig@pengutronix.de, tomasz.figa@gmail.com, linus.walleij@linaro.org, thomas.petazzoni@free-electrons.com, arnd@arndb.de Subject: Re: [PATCH v4] ARM: clocksource: add support for MOXA ART SoCs In-Reply-To: <1372687359-18235-1-git-send-email-jonas.jensen@gmail.com> Message-ID: References: <1372332203-30228-1-git-send-email-jonas.jensen@gmail.com> <1372687359-18235-1-git-send-email-jonas.jensen@gmail.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 1 Jul 2013, Jonas Jensen wrote: > +static int moxart_clkevt_next_event(unsigned long cycles, > + struct clock_event_device *unused) > +{ > + u32 u; > + > + u = readl(base + TIMER_CR) & ~TIMEREG_CR_1_ENABLE; You should cache that value and avoid another readout below. You could even cache it in general so you avoid all readouts. > + writel(u, base + TIMER_CR); > + u = readl(base + TIMER1_BASE + REG_COUNT) - cycles; > + writel(u, base + TIMER1_BASE + REG_MATCH1); > + u = readl(base + TIMER_CR) | TIMEREG_CR_1_ENABLE; > + writel(u, base + TIMER_CR); > + return 0; > +} Thanks, tglx From mboxrd@z Thu Jan 1 00:00:00 1970 From: tglx@linutronix.de (Thomas Gleixner) Date: Mon, 1 Jul 2013 19:55:15 +0200 (CEST) Subject: [PATCH v4] ARM: clocksource: add support for MOXA ART SoCs In-Reply-To: <1372687359-18235-1-git-send-email-jonas.jensen@gmail.com> References: <1372332203-30228-1-git-send-email-jonas.jensen@gmail.com> <1372687359-18235-1-git-send-email-jonas.jensen@gmail.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, 1 Jul 2013, Jonas Jensen wrote: > +static int moxart_clkevt_next_event(unsigned long cycles, > + struct clock_event_device *unused) > +{ > + u32 u; > + > + u = readl(base + TIMER_CR) & ~TIMEREG_CR_1_ENABLE; You should cache that value and avoid another readout below. You could even cache it in general so you avoid all readouts. > + writel(u, base + TIMER_CR); > + u = readl(base + TIMER1_BASE + REG_COUNT) - cycles; > + writel(u, base + TIMER1_BASE + REG_MATCH1); > + u = readl(base + TIMER_CR) | TIMEREG_CR_1_ENABLE; > + writel(u, base + TIMER_CR); > + return 0; > +} Thanks, tglx