From patchwork Mon Mar 25 18:18:19 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 2333061 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork1.kernel.org (Postfix) with ESMTP id A96833FD8C for ; Mon, 25 Mar 2013 18:26:59 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1UKC3u-0003ai-Sm; Mon, 25 Mar 2013 18:24:03 +0000 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1UKByZ-00016N-5E for linux-arm-kernel@lists.infradead.org; Mon, 25 Mar 2013 18:18:33 +0000 Received: from mudshark.cambridge.arm.com (mudshark.cambridge.arm.com [10.1.79.58]) by cam-admin0.cambridge.arm.com (8.12.6/8.12.6) with ESMTP id r2PIITki013046; Mon, 25 Mar 2013 18:18:29 GMT Received: by mudshark.cambridge.arm.com (Postfix, from userid 1000) id E01E9C2B14; Mon, 25 Mar 2013 18:18:20 +0000 (GMT) From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] ARM: delay: use private ticks_per_jiffy field for timer-based delay ops Date: Mon, 25 Mar 2013 18:18:19 +0000 Message-Id: <1364235499-17797-1-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 1.8.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130325_141831_505742_3EBA341E X-CRM114-Status: GOOD ( 13.08 ) X-Spam-Score: -8.2 (--------) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-8.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at http://www.dnswl.org/, high trust [217.140.96.50 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -1.3 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Will Deacon X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Commit 70264367a243 ("ARM: 7653/2: do not scale loops_per_jiffy when using a constant delay clock") fixed a problem with our timer-based delay loop, where loops_per_jiffy is scaled by cpufreq yet used directly by the timer delay ops. This patch fixes the problem in a more elegant way by keeping a private ticks_per_jiffy field in the delay ops, independent of loops_per_jiffy and therefore not subject to scaling. The loop-based delay continues to use loops_per_jiffy directly, as it should. Signed-off-by: Will Deacon Acked-by: Nicolas Pitre --- arch/arm/include/asm/delay.h | 2 +- arch/arm/kernel/smp.c | 3 --- arch/arm/lib/delay.c | 8 +++++--- 3 files changed, 6 insertions(+), 7 deletions(-) diff --git a/arch/arm/include/asm/delay.h b/arch/arm/include/asm/delay.h index 720799f..dff714d 100644 --- a/arch/arm/include/asm/delay.h +++ b/arch/arm/include/asm/delay.h @@ -24,7 +24,7 @@ extern struct arm_delay_ops { void (*delay)(unsigned long); void (*const_udelay)(unsigned long); void (*udelay)(unsigned long); - bool const_clock; + unsigned long ticks_per_jiffy; } arm_delay_ops; #define __delay(n) arm_delay_ops.delay(n) diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 79078ed..1f2cccc 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -673,9 +673,6 @@ static int cpufreq_callback(struct notifier_block *nb, if (freq->flags & CPUFREQ_CONST_LOOPS) return NOTIFY_OK; - if (arm_delay_ops.const_clock) - return NOTIFY_OK; - if (!per_cpu(l_p_j_ref, cpu)) { per_cpu(l_p_j_ref, cpu) = per_cpu(cpu_data, cpu).loops_per_jiffy; diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c index 6b93f6a..64dbfa5 100644 --- a/arch/arm/lib/delay.c +++ b/arch/arm/lib/delay.c @@ -58,7 +58,7 @@ static void __timer_delay(unsigned long cycles) static void __timer_const_udelay(unsigned long xloops) { unsigned long long loops = xloops; - loops *= loops_per_jiffy; + loops *= arm_delay_ops.ticks_per_jiffy; __timer_delay(loops >> UDELAY_SHIFT); } @@ -73,11 +73,13 @@ void __init register_current_timer_delay(const struct delay_timer *timer) pr_info("Switching to timer-based delay loop\n"); delay_timer = timer; lpj_fine = timer->freq / HZ; - loops_per_jiffy = lpj_fine; + + /* cpufreq may scale loops_per_jiffy, so keep a private copy */ + arm_delay_ops.ticks_per_jiffy = lpj_fine; arm_delay_ops.delay = __timer_delay; arm_delay_ops.const_udelay = __timer_const_udelay; arm_delay_ops.udelay = __timer_udelay; - arm_delay_ops.const_clock = true; + delay_calibrated = true; } else { pr_info("Ignoring duplicate/late registration of read_current_timer delay\n");