Commit 641f71f5 authored by Matt Mackall's avatar Matt Mackall Committed by Linus Torvalds
Browse files

[PATCH] RTC: Remove RTC UIP synchronization on x86_64 



Signed-off-by: default avatarMatt Mackall <mpm@selenic.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 63732c2f

arch/x86_64/kernel/time.c

+12 −29
Original line number Diff line number Diff line
@@ -504,42 +504,25 @@ 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;

	unsigned extyear = 0;



/*

 * 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.

 	 */

	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);



#ifdef CONFIG_ACPI

	if (acpi_fadt.revision >= FADT2_REVISION_ID && acpi_fadt.century)

		if (acpi_fadt.revision >= FADT2_REVISION_ID &&

					acpi_fadt.century)

			extyear = CMOS_READ(acpi_fadt.century);

#endif

	} while (sec != CMOS_READ(RTC_SECONDS));



	spin_unlock_irqrestore(&rtc_lock, flags);