From patchwork Thu Dec 18 14:05:23 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Ferre X-Patchwork-Id: 5514121 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id C5D3ABEEA8 for ; Thu, 18 Dec 2014 14:08:18 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 063F920A1B for ; Thu, 18 Dec 2014 14:08:18 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D8F3A209E1 for ; Thu, 18 Dec 2014 14:08:16 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Y1biE-0007vB-Ew; Thu, 18 Dec 2014 14:05:54 +0000 Received: from eusmtp01.atmel.com ([212.144.249.242]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Y1bi8-0007qD-8A for linux-arm-kernel@lists.infradead.org; Thu, 18 Dec 2014 14:05:49 +0000 Received: from tenerife.corp.atmel.com (10.161.101.13) by eusmtp01.atmel.com (10.161.101.30) with Microsoft SMTP Server id 14.2.347.0; Thu, 18 Dec 2014 15:05:20 +0100 From: Nicolas Ferre To: , , Subject: [PATCH] clocksource: timer-atmel-pit: don't suspend/resume if unused Date: Thu, 18 Dec 2014 15:05:23 +0100 Message-ID: <1418911523-28492-1-git-send-email-nicolas.ferre@atmel.com> X-Mailer: git-send-email 2.1.3 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20141218_060548_501080_BA5E20A0 X-CRM114-Status: UNSURE ( 9.65 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -0.0 (/) Cc: sylvain.rochet@finsecur.com, Boris BREZILLON , Maxime Ripard , Alexandre Belloni , Nicolas Ferre X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Sylvain Rochet Waiting for PIT to stop counting takes a long time: 1/(Master clock/prescaler/PIVR) = 1/(133 MHz /16 /2^20) = 126 ms Up to 126 ms if master clock is set to 133 MHz, skipping suspend/resume of the unused PIT device reduce (suspend time + resume time) from ~140 ms to ~17 ms. Signed-off-by: Sylvain Rochet [nicolas.ferre@atmel.com: move to newer clocksource driver] Signed-off-by: Nicolas Ferre Cc: Daniel Lezcano --- Hi Sylvain, I re-worked (and "Acked") your patch so it can be applied on the newer Mainline kernels. Beware, I changed the "subject line" as well. The PIT driver moved recently (3.18). Daniel, Can you take this patch in your tree? Thanks, bye. Nicolas. drivers/clocksource/timer-atmel-pit.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/clocksource/timer-atmel-pit.c b/drivers/clocksource/timer-atmel-pit.c index b5b4d4585c9a..5408bc7c68d8 100644 --- a/drivers/clocksource/timer-atmel-pit.c +++ b/drivers/clocksource/timer-atmel-pit.c @@ -123,6 +123,10 @@ static void at91sam926x_pit_suspend(struct clock_event_device *cedev) { struct pit_data *data = clkevt_to_pit_data(cedev); + /* Don't suspend PIT if unused */ + if (cedev->mode == CLOCK_EVT_MODE_UNUSED) + return; + /* Disable timer */ pit_write(data->base, AT91_PIT_MR, 0); } @@ -145,6 +149,10 @@ static void at91sam926x_pit_resume(struct clock_event_device *cedev) { struct pit_data *data = clkevt_to_pit_data(cedev); + /* Don't resume PIT if unused */ + if (cedev->mode == CLOCK_EVT_MODE_UNUSED) + return; + at91sam926x_pit_reset(data); }