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Subject[PATCH 2/3] clocksource: sun4i: Report the minimum tick that we can program
Date
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>
---
drivers/clocksource/sun4i_timer.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/clocksource/sun4i_timer.c b/drivers/clocksource/sun4i_timer.c
index 8ead025..46008f9 100644
--- a/drivers/clocksource/sun4i_timer.c
+++ b/drivers/clocksource/sun4i_timer.c
@@ -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);
--
1.8.4


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