Fix lost tick calculation in timer_pm.c Code by: Srivatsa Vaddagiri Signed-off-by: Con Kolivas arch/i386/kernel/timers/timer_pm.c | 27 +++++++++++---------------- 1 files changed, 11 insertions(+), 16 deletions(-) Index: linux-2.6.16-rc5-dt/arch/i386/kernel/timers/timer_pm.c =================================================================== --- linux-2.6.16-rc5-dt.orig/arch/i386/kernel/timers/timer_pm.c 2006-02-27 20:31:23.000000000 +1100 +++ linux-2.6.16-rc5-dt/arch/i386/kernel/timers/timer_pm.c 2006-02-27 20:32:57.000000000 +1100 @@ -29,7 +29,7 @@ #define PMTMR_TICKS_PER_SEC 3579545 #define PMTMR_EXPECTED_RATE \ ((CALIBRATE_LATCH * (PMTMR_TICKS_PER_SEC >> 10)) / (CLOCK_TICK_RATE>>10)) - +#define PMTMR_TICKS_PER_JIFFY (PMTMR_EXPECTED_RATE / (CALIBRATE_LATCH/LATCH)) /* The I/O port the PMTMR resides at. * The location is detected during setup_arch(), @@ -128,6 +128,11 @@ pm_good: if (verify_pmtmr_rate() != 0) return -ENODEV; + printk("Using %u PM timer ticks per jiffy \n", PMTMR_TICKS_PER_JIFFY); + + offset_tick = read_pmtmr(); + setup_pit_timer(); + init_cpu_khz(); set_dyntick_limits(((0xFFFFFF / 1000000) * 286 * HZ) >> 10, 0); return 0; @@ -153,7 +158,6 @@ static inline u32 cyc2us(u32 cycles) static int mark_offset_pmtmr(void) { u32 lost, delta, last_offset; - static int first_run = 1; last_offset = offset_tick; write_seqlock(&monotonic_lock); @@ -163,29 +167,19 @@ static int mark_offset_pmtmr(void) /* calculate tick interval */ delta = (offset_tick - last_offset) & ACPI_PM_MASK; - /* convert to usecs */ - delta = cyc2us(delta); - /* update the monotonic base value */ - monotonic_base += delta * NSEC_PER_USEC; + monotonic_base += cyc2us(delta) * NSEC_PER_USEC; write_sequnlock(&monotonic_lock); /* convert to ticks */ delta += offset_delay; - lost = delta / (USEC_PER_SEC / HZ); - offset_delay = delta % (USEC_PER_SEC / HZ); - + lost = delta / PMTMR_TICKS_PER_JIFFY; + offset_delay = delta % PMTMR_TICKS_PER_JIFFY; /* compensate for lost ticks */ if (lost >= 2) jiffies_64 += lost - 1; - /* don't calculate delay for first run, - or if we've got less then a tick */ - if (first_run || (lost < 1)) { - first_run = 0; - offset_delay = 0; - } return lost; } @@ -195,6 +189,7 @@ static int pmtmr_resume(void) /* Assume this is the last mark offset time */ offset_tick = read_pmtmr(); write_sequnlock(&monotonic_lock); + offset_delay = 0; return 0; } @@ -246,7 +241,7 @@ static unsigned long get_offset_pmtmr(vo now = read_pmtmr(); delta = (now - offset)&ACPI_PM_MASK; - return (unsigned long) offset_delay + cyc2us(delta); + return (unsigned long) cyc2us(delta + offset_delay); }