The current shift value in clocksource was not suitable for low frequency timer. Find the shift value in runtime to avoid undesirable overflow. Also calculate a somewhat reasonable rating value based on its frequency. Signed-off-by: Atsushi Nemoto <anemo@xxxxxxxxxxxxx> diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c index 2c6d52b..e535f86 100644 --- a/arch/mips/kernel/time.c +++ b/arch/mips/kernel/time.c @@ -324,22 +324,29 @@ static cycle_t read_mips_hpt(void) static struct clocksource clocksource_mips = { .name = "MIPS", - .rating = 250, .read = read_mips_hpt, - .shift = 24, .is_continuous = 1, }; static void __init init_mips_clocksource(void) { u64 temp; + u32 shift; if (!mips_hpt_frequency || mips_hpt_read == null_hpt_read) return; - temp = (u64) NSEC_PER_SEC << clocksource_mips.shift; - do_div(temp, mips_hpt_frequency); - clocksource_mips.mult = (unsigned)temp; + /* Calclate a somewhat reasonable rating value */ + clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000; + /* Find a shift value */ + for (shift = 32; shift > 0; shift--) { + temp = (u64) NSEC_PER_SEC << shift; + do_div(temp, mips_hpt_frequency); + if ((temp >> 32) == 0) + break; + } + clocksource_mips.shift = shift; + clocksource_mips.mult = (u32)temp; clocksource_mips.mask = mips_hpt_mask; clocksource_register(&clocksource_mips);