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Subject[PATCH 2/14] RTC: Remove RTC UIP synchronization on x86_64
Date
Remove RTC UIP synchronization on x86_64

Signed-off-by: Matt Mackall <mpm@selenic.com>

Index: rtc/arch/x86_64/kernel/time.c
===================================================================
--- rtc.orig/arch/x86_64/kernel/time.c 2006-03-16 16:48:38.000000000 -0600
+++ rtc/arch/x86_64/kernel/time.c 2006-03-16 17:21:17.000000000 -0600
@@ -514,36 +514,19 @@ unsigned long long sched_clock(void)

static unsigned long get_cmos_time(void)
{
- unsigned int timeout = 1000000, year, mon, day, hour, min, sec;
- unsigned char uip = 0, this = 0;
+ unsigned int year, mon, day, hour, min, sec;
unsigned long flags;

-/*
- * The Linux interpretation of the CMOS clock register contents: When the
- * Update-In-Progress (UIP) flag goes from 1 to 0, the RTC registers show the
- * second which has precisely just started. Waiting for this can take up to 1
- * second, we timeout approximately after 2.4 seconds on a machine with
- * standard 8.3 MHz ISA bus.
- */
-
spin_lock_irqsave(&rtc_lock, flags);

- while (timeout && (!uip || this)) {
- uip |= this;
- this = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP;
- timeout--;
- }
-
- /*
- * Here we are safe to assume the registers won't change for a whole
- * second, so we just go ahead and read them.
- */
- sec = CMOS_READ(RTC_SECONDS);
- min = CMOS_READ(RTC_MINUTES);
- hour = CMOS_READ(RTC_HOURS);
- day = CMOS_READ(RTC_DAY_OF_MONTH);
- mon = CMOS_READ(RTC_MONTH);
- year = CMOS_READ(RTC_YEAR);
+ do {
+ sec = CMOS_READ(RTC_SECONDS);
+ min = CMOS_READ(RTC_MINUTES);
+ hour = CMOS_READ(RTC_HOURS);
+ day = CMOS_READ(RTC_DAY_OF_MONTH);
+ mon = CMOS_READ(RTC_MONTH);
+ year = CMOS_READ(RTC_YEAR);
+ } while (sec != CMOS_READ(RTC_SECONDS));

spin_unlock_irqrestore(&rtc_lock, flags);

-
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