From: Zhao Yakui Date: Wed, 2 Jun 2010 03:04:09 +0000 (+0800) Subject: ACPI: Fix the incorrect calculation about C-state idle time X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=157317ba3ec3e5a4d9683b8d24ba40b4f8f3296b;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git ACPI: Fix the incorrect calculation about C-state idle time The C-state idle time is not calculated correctly, which will return the wrong residency time in C-state. It will have the following effects: 1. The system can't choose the deeper C-state when it is idle next time. Of course the system power is increased. E.g. On one server machine about 40W idle power is increased. 2. The powertop shows that it will stay in C0 running state about 95% time although the system is idle at most time. 2.6.35-rc1 regression caused-by: 2da513f582a96c053aacc2c92873978d2ea7abff (ACPI: Minor cleanup eliminating redundant PMTIMER_TICKS to NS conversion) Signed-off-by: Zhao Yakui Reported-by: Yu Zhidong Tested-by: Yu Zhidong Acked-by: Venkatesh Pallipadi Signed-off-by: Len Brown --- diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 2e8c27d48f2b..6b38a6b43ce8 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -1022,7 +1022,7 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev, spin_unlock(&c3_lock); } kt2 = ktime_get_real(); - idle_time_ns = ktime_to_us(ktime_sub(kt2, kt1)); + idle_time_ns = ktime_to_ns(ktime_sub(kt2, kt1)); idle_time = idle_time_ns; do_div(idle_time, NSEC_PER_USEC);