From mboxrd@z Thu Jan 1 00:00:00 1970 From: mkl@pengutronix.de (Marc Kleine-Budde) Date: Tue, 23 Apr 2013 15:50:37 +0200 Subject: RFC: [PATCH] clocksource: tcb: fix min_delta calculation In-Reply-To: <20130423134448.GG27475@S2101-09.ap.freescale.net> References: <517687AB.1040309@pengutronix.de> <1366722524-25991-1-git-send-email-mkl@pengutronix.de> <51768885.4080301@pengutronix.de> <20130423134448.GG27475@S2101-09.ap.freescale.net> Message-ID: <517691AD.304@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 04/23/2013 03:44 PM, Shawn Guo wrote: > On Tue, Apr 23, 2013 at 03:11:33PM +0200, Marc Kleine-Budde wrote: >> On 04/23/2013 03:08 PM, Marc Kleine-Budde wrote: >>> The commit >>> >>> 77cc982 clocksource: use clockevents_config_and_register() where possible >>> >>> switches from manually calculating min_delta_ns (and others) and >>> clockevents_register_device() to automatic calculation via >>> clockevents_config_and_register(). During this conversation the "+ 1" in >>> >>> min_delta_ns = clockevent_delta2ns(1, &clkevt.clkevt) + 1; >>> >>> was lost. This leads to problems with schedule_delayed_work() with a delay of >>> "1". Resulting in the work not scheduled in time. >>> >>> This patch fixes the problem by increasing the min_delta to "2" ticks. >>> >>> Signed-off-by: Marc Kleine-Budde >> >> The problem appears on at91sam9263. This patch successfully fixes the >> problem and applies to current linus/master (post v3.9-rc8). > > Thanks for the fixing, Marc. > > Acked-by: Shawn Guo Thanks. The downside of my RFC Patch is, that min_delta_ns is increased from 30518 to 61035: good: setup_clkevents: shift=32 mult=140737 min=30518 max=1999976422 bad: setup_clkevents: shift=32 mult=140737 min=30517 max=1999976422 RFC: setup_clkevents: shift=32 mult=140737 min=61035 max=1999976422 To keep the original min_delta_ns value of 30518, a rather hackish option would be this: diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c index 8a61872..30e0a68 100644 --- a/drivers/clocksource/tcb_clksrc.c +++ b/drivers/clocksource/tcb_clksrc.c @@ -198,6 +198,7 @@ static void __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx) clkevt.clkevt.cpumask = cpumask_of(0); clockevents_config_and_register(&clkevt.clkevt, 32768, 1, 0xffff); + clkevt.clkevt.min_delta_ns = clockevent_delta2ns(1, &clkevt.clkevt) + 1; setup_irq(irq, &tc_irqaction); } Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 263 bytes Desc: OpenPGP digital signature URL: