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Commit 08e4b448 authored by Jisheng Zhang's avatar Jisheng Zhang Committed by Daniel Lezcano
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clockevents/drivers/arm_global_timer: Use writel_relaxed in gt_compare_set 



Use the relaxed version to improve performance. we measured time of
4096 rounds of gt_compare_set() spent on Marvell BG2Q:

before the patch: 3690648ns on average
after the patch: 1083023ns on average

improved by 70%!

Signed-off-by: default avatarJisheng Zhang <jszhang@marvell.com>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
parent 520ddad4

drivers/clocksource/arm_global_timer.c

+5 −5
Original line number Diff line number Diff line
@@ -99,17 +99,17 @@ static void gt_compare_set(unsigned long delta, int periodic) 


	counter += delta;

	ctrl = GT_CONTROL_TIMER_ENABLE;

	writel(ctrl, gt_base + GT_CONTROL);

	writel(lower_32_bits(counter), gt_base + GT_COMP0);

	writel(upper_32_bits(counter), gt_base + GT_COMP1);

	writel_relaxed(ctrl, gt_base + GT_CONTROL);

	writel_relaxed(lower_32_bits(counter), gt_base + GT_COMP0);

	writel_relaxed(upper_32_bits(counter), gt_base + GT_COMP1);



	if (periodic) {

		writel(delta, gt_base + GT_AUTO_INC);

		writel_relaxed(delta, gt_base + GT_AUTO_INC);

		ctrl |= GT_CONTROL_AUTO_INC;

	}



	ctrl |= GT_CONTROL_COMP_ENABLE | GT_CONTROL_IRQ_ENABLE;

	writel(ctrl, gt_base + GT_CONTROL);

	writel_relaxed(ctrl, gt_base + GT_CONTROL);

}



static int gt_clockevent_shutdown(struct clock_event_device *evt)