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Date: Thu, 6 Mar 2014 09:45:36 +0800 From: Shawn Guo <shawn.guo@...aro.org> To: Stefan Agner <stefan@...er.ch> CC: <daniel.lezcano@...aro.org>, <tglx@...utronix.de>, <linux@....linux.org.uk>, <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>, Jingchang Lu <b35083@...escale.com> Subject: Re: [PATCH] clocksource: vf_pit_timer: use complement for sched_clock reading On Wed, Mar 05, 2014 at 11:11:08PM +0100, Stefan Agner wrote: > Vybrids PIT register is monitonic decreasing. However, sched_clock > reading needs to be monitonic increasing. Use bitwise not to get > the complement of the clock register. This fixes the clock going > backward. Also, the clock now starts at 0 since we load the > register with the maximum value at start. > > Signed-off-by: Stefan Agner <stefan@...er.ch> Looks correct to me, so Acked-by: Shawn Guo <shawn.guo@...aro.org> But I also copied the driver author Jingchang to see if he has any comment. Shawn > --- > drivers/clocksource/vf_pit_timer.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/clocksource/vf_pit_timer.c b/drivers/clocksource/vf_pit_timer.c > index 02821b0..a918bc4 100644 > --- a/drivers/clocksource/vf_pit_timer.c > +++ b/drivers/clocksource/vf_pit_timer.c > @@ -54,7 +54,7 @@ static inline void pit_irq_acknowledge(void) > > static u64 pit_read_sched_clock(void) > { > - return __raw_readl(clksrc_base + PITCVAL); > + return ~__raw_readl(clksrc_base + PITCVAL); > } > > static int __init pit_clocksource_init(unsigned long rate) > -- > 1.9.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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