From b20367a6c2a0cd937cb1f0a8cf848f1402fef99c Mon Sep 17 00:00:00 2001 From: Jordan Hargrave Date: Fri, 7 Apr 2006 19:50:18 +0200 Subject: [PATCH] x86_64: Fix drift with HPET timer enabled If the HPET timer is enabled, the clock can drift by ~3 seconds a day. This is due to the HPET timer not being initialized with the correct setting (still using PIT count). If HZ changes, this drift can become even more pronounced. HPET patch initializes tick_nsec with correct tick_nsec settings for HPET timer. Vojtech comments: "It's not entirely correct (it assumes the HPET ticks totally exactly), but it's significantly better than assuming the PIT error there." Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- include/asm-i386/hpet.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/asm-i386/hpet.h') diff --git a/include/asm-i386/hpet.h b/include/asm-i386/hpet.h index 16ef9f9..7f1a8a6 100644 --- a/include/asm-i386/hpet.h +++ b/include/asm-i386/hpet.h @@ -89,6 +89,7 @@ * then 32 bit HPET counter wrapsaround in less than 0.5 sec. */ #define HPET_MIN_PERIOD (100000UL) +#define HPET_TICK_RATE (HZ * 100000UL) extern unsigned long hpet_tick; /* hpet clks count per tick */ extern unsigned long hpet_address; /* hpet memory map physical address */ -- cgit v1.1