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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: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
This commit is contained in:
Jisheng Zhang 2015-11-26 20:20:38 +08:00 committed by Daniel Lezcano
parent 520ddad4e5
commit 08e4b44852
1 changed files with 5 additions and 5 deletions
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10
drivers/clocksource/arm_global_timer.c
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@ -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)