Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752564AbaLROF3 (ORCPT ); Thu, 18 Dec 2014 09:05:29 -0500 Received: from eusmtp01.atmel.com ([212.144.249.242]:15157 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752458AbaLROF2 (ORCPT ); Thu, 18 Dec 2014 09:05:28 -0500 From: Nicolas Ferre To: , , CC: Boris BREZILLON , Alexandre Belloni , Maxime Ripard , , Nicolas Ferre 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 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); } -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/