diff options
Diffstat (limited to 'drivers/clocksource/timer-rtl-otto.c')
| -rw-r--r-- | drivers/clocksource/timer-rtl-otto.c | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/drivers/clocksource/timer-rtl-otto.c b/drivers/clocksource/timer-rtl-otto.c index 8a3068b36e75..24c4aa6a3013 100644 --- a/drivers/clocksource/timer-rtl-otto.c +++ b/drivers/clocksource/timer-rtl-otto.c @@ -38,6 +38,7 @@ #define RTTM_BIT_COUNT 28 #define RTTM_MIN_DELTA 8 #define RTTM_MAX_DELTA CLOCKSOURCE_MASK(28) +#define RTTM_MAX_DIVISOR GENMASK(15, 0) /* * Timers are derived from the LXB clock frequency. Usually this is a fixed @@ -112,6 +113,22 @@ static irqreturn_t rttm_timer_interrupt(int irq, void *dev_id) return IRQ_HANDLED; } +static void rttm_bounce_timer(void __iomem *base, u32 mode) +{ + /* + * When a running timer has less than ~5us left, a stop/start sequence + * might fail. While the details are unknown the most evident effect is + * that the subsequent interrupt will not be fired. + * + * As a workaround issue an intermediate restart with a very slow + * frequency of ~3kHz keeping the target counter (>=8). So the follow + * up restart will always be issued outside the critical window. + */ + + rttm_disable_timer(base); + rttm_enable_timer(base, mode, RTTM_MAX_DIVISOR); +} + static void rttm_stop_timer(void __iomem *base) { rttm_disable_timer(base); @@ -129,7 +146,8 @@ static int rttm_next_event(unsigned long delta, struct clock_event_device *clkev struct timer_of *to = to_timer_of(clkevt); RTTM_DEBUG(to->of_base.base); - rttm_stop_timer(to->of_base.base); + rttm_bounce_timer(to->of_base.base, RTTM_CTRL_COUNTER); + rttm_disable_timer(to->of_base.base); rttm_set_period(to->of_base.base, delta); rttm_start_timer(to, RTTM_CTRL_COUNTER); @@ -141,7 +159,8 @@ static int rttm_state_oneshot(struct clock_event_device *clkevt) struct timer_of *to = to_timer_of(clkevt); RTTM_DEBUG(to->of_base.base); - rttm_stop_timer(to->of_base.base); + rttm_bounce_timer(to->of_base.base, RTTM_CTRL_COUNTER); + rttm_disable_timer(to->of_base.base); rttm_set_period(to->of_base.base, RTTM_TICKS_PER_SEC / HZ); rttm_start_timer(to, RTTM_CTRL_COUNTER); @@ -153,7 +172,8 @@ static int rttm_state_periodic(struct clock_event_device *clkevt) struct timer_of *to = to_timer_of(clkevt); RTTM_DEBUG(to->of_base.base); - rttm_stop_timer(to->of_base.base); + rttm_bounce_timer(to->of_base.base, RTTM_CTRL_TIMER); + rttm_disable_timer(to->of_base.base); rttm_set_period(to->of_base.base, RTTM_TICKS_PER_SEC / HZ); rttm_start_timer(to, RTTM_CTRL_TIMER); |