From 359b47db9799b72aa50aa07bacd838206a7b7b23 Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Thu, 21 Mar 2013 15:42:41 +0000 Subject: [PATCH] Minimal timer period of 100us introduced in r244758 is overkill. While original 2us are indeed not enough, 3us are working quite well on my tests. To be more safe set minimal period to 5us and to be even more safe replicate here from HPET mechanism of rereading counter after programming comparator. This change allows to handle 30K of short nanosleep() calls per second on Raspberry Pi instead of just 8K before. Discussed with: gonzo --- sys/arm/broadcom/bcm2835/bcm2835_systimer.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/sys/arm/broadcom/bcm2835/bcm2835_systimer.c b/sys/arm/broadcom/bcm2835/bcm2835_systimer.c index 1d7fddaea8f8..40af90d79cd5 100644 --- a/sys/arm/broadcom/bcm2835/bcm2835_systimer.c +++ b/sys/arm/broadcom/bcm2835/bcm2835_systimer.c @@ -55,7 +55,7 @@ __FBSDID("$FreeBSD$"); #define DEFAULT_TIMER 3 #define DEFAULT_FREQUENCY 1000000 -#define MIN_PERIOD 100LLU +#define MIN_PERIOD 5LLU #define SYSTIMER_CS 0x00 #define SYSTIMER_CLO 0x04 @@ -121,7 +121,7 @@ static int bcm_systimer_start(struct eventtimer *et, sbintime_t first, sbintime_t period) { struct systimer *st = et->et_priv; - uint32_t clo; + uint32_t clo, clo1; uint32_t count; register_t s; @@ -131,12 +131,19 @@ bcm_systimer_start(struct eventtimer *et, sbintime_t first, sbintime_t period) s = intr_disable(); clo = bcm_systimer_tc_read_4(SYSTIMER_CLO); +restart: clo += count; /* * Clear pending interrupts */ bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index)); bcm_systimer_tc_write_4(SYSTIMER_C0 + st->index*4, clo); + clo1 = bcm_systimer_tc_read_4(SYSTIMER_CLO); + if ((int32_t)(clo1 - clo) >= 0) { + count *= 2; + clo = clo1; + goto restart; + } st->enabled = 1; intr_restore(s); @@ -236,9 +243,9 @@ bcm_systimer_attach(device_t dev) sc->st[DEFAULT_TIMER].et.et_quality = 1000; sc->st[DEFAULT_TIMER].et.et_frequency = sc->sysclk_freq; sc->st[DEFAULT_TIMER].et.et_min_period = - (MIN_PERIOD << 32) / sc->st[DEFAULT_TIMER].et.et_frequency; + (MIN_PERIOD << 32) / sc->st[DEFAULT_TIMER].et.et_frequency + 1; sc->st[DEFAULT_TIMER].et.et_max_period = - (0xfffffffeLLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency; + (0x7ffffffeLLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency; sc->st[DEFAULT_TIMER].et.et_start = bcm_systimer_start; sc->st[DEFAULT_TIMER].et.et_stop = bcm_systimer_stop; sc->st[DEFAULT_TIMER].et.et_priv = &sc->st[DEFAULT_TIMER];