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clocksource: sun4i: Report the minimum tick that we can program 

We need to wait for at least 2 clock cycles whenever we reprogram our
clockevent timer. Report that the minimum number of ticks we can handle
is 3 ticks, and remove 3 ticks to the interval programmed to reflect
this.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
This commit is contained in:
Maxime Ripard 2013-10-14 21:07:47 +02:00 committed by Daniel Lezcano
parent 71c568c000
commit 12e1480bcb
1 changed files with 6 additions and 4 deletions
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10
drivers/clocksource/sun4i_timer.c
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@ -37,6 +37,8 @@
#define TIMER_INTVAL_REG(val) (0x10 * (val) + 0x14)
#define TIMER_CNTVAL_REG(val) (0x10 * (val) + 0x18)
#define TIMER_SYNC_TICKS 3
static void __iomem *timer_base;
static u32 ticks_per_jiffy;
@ -50,7 +52,7 @@ static void sun4i_clkevt_sync(void)
{
u32 old = readl(timer_base + TIMER_CNTVAL_REG(1));
while ((old - readl(timer_base + TIMER_CNTVAL_REG(1))) < 3)
while ((old - readl(timer_base + TIMER_CNTVAL_REG(1))) < TIMER_SYNC_TICKS)
cpu_relax();
}
@ -104,7 +106,7 @@ static int sun4i_clkevt_next_event(unsigned long evt,
struct clock_event_device *unused)
{
sun4i_clkevt_time_stop(0);
sun4i_clkevt_time_setup(0, evt);
sun4i_clkevt_time_setup(0, evt - TIMER_SYNC_TICKS);
sun4i_clkevt_time_start(0, false);
return 0;
@ -187,8 +189,8 @@ static void __init sun4i_timer_init(struct device_node *node)
sun4i_clockevent.cpumask = cpumask_of(0);
clockevents_config_and_register(&sun4i_clockevent, rate, 0x1,
0xffffffff);
clockevents_config_and_register(&sun4i_clockevent, rate,
TIMER_SYNC_TICKS, 0xffffffff);
}
CLOCKSOURCE_OF_DECLARE(sun4i, "allwinner,sun4i-timer",
sun4i_timer_init);