diff options
Diffstat (limited to 'arch/x86/kernel/hpet.c')
| -rw-r--r-- | arch/x86/kernel/hpet.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index ee4fa1bfcb33..23b4ecdffa9b 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -4,6 +4,7 @@ #include <linux/sysdev.h> #include <linux/delay.h> #include <linux/errno.h> +#include <linux/slab.h> #include <linux/hpet.h> #include <linux/init.h> #include <linux/cpu.h> @@ -399,9 +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; } @@ -1143,6 +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; } |