diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/tsc.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 599e58168631..9e80207c96a2 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -315,6 +315,15 @@ static unsigned long quick_pit_calibrate(void) outb(0xff, 0x42); outb(0xff, 0x42); + /* + * The PIT starts counting at the next edge, so we + * need to delay for a microsecond. The easiest way + * to do that is to just read back the 16-bit counter + * once from the PIT. + */ + inb(0x42); + inb(0x42); + if (pit_expect_msb(0xff)) { int i; u64 t1, t2, delta; |