From patchwork Tue Oct 23 05:57:34 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Felipe Balbi X-Patchwork-Id: 1628811 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 035FC3FC1A for ; Tue, 23 Oct 2012 06:07:12 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TQXbP-0002J1-FW; Tue, 23 Oct 2012 06:04:35 +0000 Received: from bear.ext.ti.com ([192.94.94.41]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TQXbI-0002In-Kn for linux-arm-kernel@lists.infradead.org; Tue, 23 Oct 2012 06:04:30 +0000 Received: from dlelxv30.itg.ti.com ([172.17.2.17]) by bear.ext.ti.com (8.13.7/8.13.7) with ESMTP id q9N63FFB030637; Tue, 23 Oct 2012 01:03:15 -0500 Received: from DFLE72.ent.ti.com (dfle72.ent.ti.com [128.247.5.109]) by dlelxv30.itg.ti.com (8.13.8/8.13.8) with ESMTP id q9N63FTP006300; Tue, 23 Oct 2012 01:03:15 -0500 Received: from dlelxv22.itg.ti.com (172.17.1.197) by dfle72.ent.ti.com (128.247.5.109) with Microsoft SMTP Server id 14.1.323.3; Tue, 23 Oct 2012 01:03:15 -0500 Received: from localhost (h64-6.vpn.ti.com [172.24.64.6]) by dlelxv22.itg.ti.com (8.13.8/8.13.8) with ESMTP id q9N63DlQ016142; Tue, 23 Oct 2012 01:03:14 -0500 From: Felipe Balbi To: Russell King Subject: [PATCH v2] arm: sched: stop sched_clock() during suspend Date: Tue, 23 Oct 2012 08:57:34 +0300 Message-ID: <1350971854-9161-1-git-send-email-balbi@ti.com> X-Mailer: git-send-email 1.8.0.rc0 In-Reply-To: <873916h1yi.fsf@deeprootsystems.com> References: <873916h1yi.fsf@deeprootsystems.com> MIME-Version: 1.0 X-Spam-Note: CRM114 invocation failed X-Spam-Score: -4.6 (----) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-4.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- 3.0 KHOP_BIG_TO_CC Sent to 10+ recipients instaed of Bcc or a list -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at http://www.dnswl.org/, high trust [192.94.94.41 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.7 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: Andrew Lunn , Thomas Gleixner , Tony Lindgren , linus.walleij@linaro.org, Daniel Walker , Lennert Buytenhek , Kevin Hilman , Kukjin Kim , Barry Song <21cnbao@gmail.com>, Bryan Huntsman , khilman@deeprootsystems.com, David Brown , Arnd Bergmann , Stephen Warren , John Stultz , Ben Dooks , Alexander Schulz , Linux OMAP Mailing List , Andrew Victor , Linux ARM Kernel Mailing List , Paul Walmsley , Linux Kernel Mailing List , Felipe Balbi , Kyungmin Park , Santosh Shilimkar , Sascha Hauer , Colin Cross , Olof Johansson X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org The scheduler imposes a requirement to sched_clock() which is to stop the clock during suspend, if we don't do that any RT thread will be rescheduled in the future which might cause any sort of problems. This became an issue on OMAP when we converted omap-i2c.c to use threaded IRQs, it turned out that depending on how much time we spent on suspend, the I2C IRQ thread would end up being rescheduled so far in the future that I2C transfers would timeout and, because omap_hsmmc depends on an I2C-connected device to detect if an MMC card is inserted in the slot, our rootfs would just vanish. arch/arm/kernel/sched_clock.c already had an optional implementation (sched_clock_needs_suspend()) which would handle scheduler's requirement properly, what this patch does is simply to make that implementation non-optional. Note that this has the side-effect that printk timings won't reflect the actual time spent on suspend so other methods to measure that will have to be used. This has been tested with beagleboard XM (OMAP3630) and pandaboard rev A3 (OMAP4430). Suspend to RAM is now working after this patch. Signed-off-by: Felipe Balbi Acked-by: Kevin Hilman --- Changes since v1: - changed commit log to mention that all RT threads will be rescheduled to the future. - changed commit log to mention the side effect on printk timings arch/arm/include/asm/sched_clock.h | 2 -- arch/arm/kernel/sched_clock.c | 18 ++++-------------- 2 files changed, 4 insertions(+), 16 deletions(-) diff --git a/arch/arm/include/asm/sched_clock.h b/arch/arm/include/asm/sched_clock.h index 05b8e82..e3f7572 100644 --- a/arch/arm/include/asm/sched_clock.h +++ b/arch/arm/include/asm/sched_clock.h @@ -10,7 +10,5 @@ extern void sched_clock_postinit(void); extern void setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate); -extern void setup_sched_clock_needs_suspend(u32 (*read)(void), int bits, - unsigned long rate); #endif diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c index e21bac2..fc6692e 100644 --- a/arch/arm/kernel/sched_clock.c +++ b/arch/arm/kernel/sched_clock.c @@ -107,13 +107,6 @@ static void sched_clock_poll(unsigned long wrap_ticks) update_sched_clock(); } -void __init setup_sched_clock_needs_suspend(u32 (*read)(void), int bits, - unsigned long rate) -{ - setup_sched_clock(read, bits, rate); - cd.needs_suspend = true; -} - void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) { unsigned long r, w; @@ -189,18 +182,15 @@ void __init sched_clock_postinit(void) static int sched_clock_suspend(void) { sched_clock_poll(sched_clock_timer.data); - if (cd.needs_suspend) - cd.suspended = true; + cd.suspended = true; return 0; } static void sched_clock_resume(void) { - if (cd.needs_suspend) { - cd.epoch_cyc = read_sched_clock(); - cd.epoch_cyc_copy = cd.epoch_cyc; - cd.suspended = false; - } + cd.epoch_cyc = read_sched_clock(); + cd.epoch_cyc_copy = cd.epoch_cyc; + cd.suspended = false; } static struct syscore_ops sched_clock_ops = {