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authorChris Wilson <chris@chris-wilson.co.uk>2010-08-09 14:20:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-08-12 09:53:39 -0700
commit4936a3b90d79dd8775c6ac23c2cf2dcebe29abde (patch)
treeab4fb288fd00bb50b5aebcc93fa476cc2c1d53be /arch/x86/kernel/hpet.c
parentdeda2e81961e96be4f2c09328baca4710a2fd1a0 (diff)
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/x86/kernel/hpet.c')
-rw-r--r--arch/x86/kernel/hpet.c4
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);