Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[safe/jmp/linux-2.6] / arch / x86 / kernel / hpet.c

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index d10a7e7..23b4ecd 100644 (file)
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -400,9 +400,15 @@ static int hpet_next_event(unsigned long delta,
         * then we might have a real hardware problem. We can not do
         * much about it here, but at least alert the user/admin with
         * a prominent warning.
+        * An erratum on some chipsets (ICH9,..), results in comparator read
+        * immediately following a write returning old value. Workaround
+        * for this is to read this value second time, when first
+        * read returns old value.
         */
-       WARN_ONCE(hpet_readl(HPET_Tn_CMP(timer)) != cnt,
+       if (unlikely((u32)hpet_readl(HPET_Tn_CMP(timer)) != cnt)) {
+               WARN_ONCE(hpet_readl(HPET_Tn_CMP(timer)) != cnt,
                  KERN_WARNING "hpet: compare register read back failed.\n");
+       }
 
        return (s32)(hpet_readl(HPET_COUNTER) - cnt) >= 0 ? -ETIME : 0;
 }
@@ -1144,6 +1150,7 @@ int hpet_set_periodic_freq(unsigned long freq)
                do_div(clc, freq);
                clc >>= hpet_clockevent.shift;
                hpet_pie_delta = clc;
+               hpet_pie_limit = 0;
        }
        return 1;
 }