[PATCH] hpet-RTC: disable interrupt when no longer needed

When the emulated RTC interrupt is no longer needed, we better disable it;
otherwise, we get a spurious interrupt whenever the timer has rolled over and
reaches the same comparator value.

Having a superfluous interrupt every five minutes doesn't hurt much, but it's
bad style anyway.  ;-)

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Acked-by: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 10 insertions, 2 deletions

diff --git a/arch/i386/kernel/time_hpet.c b/arch/i386/kernel/time_hpet.c
index 658c0629ba6a..23e81fcbeaea 100644
--- a/arch/i386/kernel/time_hpet.c
+++ b/arch/i386/kernel/time_hpet.c
@@ -319,8 +319,12 @@ static void hpet_rtc_timer_reinit(void)
 {
         unsigned int cfg, cnt;
 
-        if (!(PIE_on | AIE_on | UIE_on))
+        if (unlikely(!(PIE_on | AIE_on | UIE_on))) {
+                cfg = hpet_readl(HPET_T1_CFG);
+                cfg &= ~HPET_TN_ENABLE;
+                hpet_writel(cfg, HPET_T1_CFG);
                 return;
+        }
 
         if (PIE_on && (PIE_freq > DEFAULT_RTC_INT_FREQ))
                 hpet_rtc_int_freq = PIE_freq;
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index bd5ea09bfdf9..7037ca668c63 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -1138,8 +1138,12 @@ static void hpet_rtc_timer_reinit(void)
 {
         unsigned int cfg, cnt;
 
-        if (!(PIE_on | AIE_on | UIE_on))
+        if (unlikely(!(PIE_on | AIE_on | UIE_on))) {
+                cfg = hpet_readl(HPET_T1_CFG);
+                cfg &= ~HPET_TN_ENABLE;
+                hpet_writel(cfg, HPET_T1_CFG);
                 return;
+        }
 
         if (PIE_on && (PIE_freq > DEFAULT_RTC_INT_FREQ))
                 hpet_rtc_int_freq = PIE_freq;