diff options
Diffstat (limited to 'sys/isa/atrtc.c')
| -rw-r--r-- | sys/isa/atrtc.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/sys/isa/atrtc.c b/sys/isa/atrtc.c index c659741..4d393b0 100644 --- a/sys/isa/atrtc.c +++ b/sys/isa/atrtc.c @@ -691,6 +691,28 @@ set_timer_freq(u_int freq, int intr_freq) } /* + * i8254_restore is called from apm_default_resume() to reload + * the countdown register. + * this should not be necessary but there are broken laptops that + * do not restore the countdown register on resume. + * when it happnes, it messes up the hardclock interval and system clock, + * which leads to the infamous "calcru: negative time" problem. + */ +void +i8254_restore(void) +{ + u_long ef; + + ef = read_eflags(); + disable_intr(); + outb(TIMER_MODE, TIMER_SEL0 | TIMER_RATEGEN | TIMER_16BIT); + outb(TIMER_CNTR0, timer0_max_count & 0xff); + outb(TIMER_CNTR0, timer0_max_count >> 8); + CLOCK_UNLOCK(); + write_eflags(ef); +} + +/* * Initialize 8254 timer 0 early so that it can be used in DELAY(). * XXX initialization of other timers is unintentionally left blank. */ |
