diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2010-08-10 01:20:10 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-12 20:53:39 +0400 |
| commit | 4936a3b90d79dd8775c6ac23c2cf2dcebe29abde (patch) | |
| tree | ab4fb288fd00bb50b5aebcc93fa476cc2c1d53be /arch | |
| parent | deda2e81961e96be4f2c09328baca4710a2fd1a0 (diff) | |
| download | linux-4936a3b90d79dd8775c6ac23c2cf2dcebe29abde.tar.xz | |
x86/hpet: Use the FSEC_PER_SEC constant for femto-second periods
The current computation, introduced with f12a15be63, of FSEC_PER_SEC using
the multiplication of (FSEC_PER_NSEC * NSEC_PER_SEC) is performed only
with 32bit integers on small machines, resulting in an overflow and a
*very* short intervals being programmed. An interrupt storm follows.
Note that we also have to specify FSEC_PER_SEC as being long long to
overcome the same limitations.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/hpet.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index 33dbcc4ec5ff..351f9c0fea1f 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -582,7 +582,7 @@ static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu) * scaled math multiplication factor for nanosecond to hpet tick * conversion. */ - hpet_freq = 1000000000000000ULL; + hpet_freq = FSEC_PER_SEC; do_div(hpet_freq, hpet_period); evt->mult = div_sc((unsigned long) hpet_freq, NSEC_PER_SEC, evt->shift); @@ -837,7 +837,7 @@ static int hpet_clocksource_register(void) * cyc/sec = FSEC_PER_SEC/hpet_period(fsec/cyc) * cyc/sec = (FSEC_PER_NSEC * NSEC_PER_SEC)/hpet_period */ - hpet_freq = FSEC_PER_NSEC * NSEC_PER_SEC; + hpet_freq = FSEC_PER_SEC; do_div(hpet_freq, hpet_period); clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq); |