[PATCH] RTC: Remove RTC UIP synchronization on PPC CHRP (arch/ppc)

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 20 deletions

diff --git a/arch/ppc/platforms/chrp_time.c b/arch/ppc/platforms/chrp_time.c
index c862777..e103a36 100644
--- a/arch/ppc/platforms/chrp_time.c
+++ b/arch/ppc/platforms/chrp_time.c
@@ -119,33 +119,15 @@ int chrp_set_rtc_time(unsigned long nowtime)
 unsigned long chrp_get_rtc_time(void)
 {
 	unsigned int year, mon, day, hour, min, sec;
-	int uip, i;
 
-	/* 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.
-	 * Let's hope other operating systems interpret the RTC the same way.
-	 */
-
-	/* Since the UIP flag is set for about 2.2 ms and the clock
-	 * is typically written with a precision of 1 jiffy, trying
-	 * to obtain a precision better than a few milliseconds is
-	 * an illusion. Only consistency is interesting, this also
-	 * allows to use the routine for /dev/rtc without a potential
-	 * 1 second kernel busy loop triggered by any reader of /dev/rtc.
-	 */
-
-	for ( i = 0; i<1000000; i++) {
-		uip = chrp_cmos_clock_read(RTC_FREQ_SELECT);
+	do {
 		sec = chrp_cmos_clock_read(RTC_SECONDS);
 		min = chrp_cmos_clock_read(RTC_MINUTES);
 		hour = chrp_cmos_clock_read(RTC_HOURS);
 		day = chrp_cmos_clock_read(RTC_DAY_OF_MONTH);
 		mon = chrp_cmos_clock_read(RTC_MONTH);
 		year = chrp_cmos_clock_read(RTC_YEAR);
-		uip |= chrp_cmos_clock_read(RTC_FREQ_SELECT);
-		if ((uip & RTC_UIP)==0) break;
-	}
+	} while (sec != chrp_cmos_clock_read(RTC_SECONDS));
 
 	if (!(chrp_cmos_clock_read(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
 	  {