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authorLinus Torvalds <torvalds@linux-foundation.org>2010-04-07 11:02:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-04-07 11:02:23 -0700
commitfb1ae635772d679eb312fa447290fc02cd0e4cf1 (patch)
tree45733f9820da1190cd58bfff080edbb02af961a8 /arch/x86/kernel/hpet.c
parentaddb2d6c13993060ae75f5005815b19dd2abdd64 (diff)
parent472a474c6630efd195d3738339fd1bdc8aa3b1aa (diff)
Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip: x86: Fix double enable_IR_x2apic() call on SMP kernel on !SMP boards x86: Increase CONFIG_NODES_SHIFT max to 10 ibft, x86: Change reserve_ibft_region() to find_ibft_region() x86, hpet: Fix bug in RTC emulation x86, hpet: Erratum workaround for read after write of HPET comparator bootmem, x86: Fix 32bit numa system without RAM on node 0 nobootmem, x86: Fix 32bit numa system without RAM on node 0 x86: Handle overlapping mptables x86: Make e820_remove_range to handle all covered case x86-32, resume: do a global tlb flush in S4 resume
Diffstat (limited to 'arch/x86/kernel/hpet.c')
-rw-r--r--arch/x86/kernel/hpet.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index d10a7e7294f..23b4ecdffa9 100644
--- 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;
}