Re: [PATCH 2/3] intel_idle: Removing the redundant calculating fordev->state_count

From: Daniel Lezcano
Date: Fri Mar 08 2013 - 22:00:30 EST


On 03/08/2013 04:04 PM, Chuansheng Liu wrote:
>
> In function intel_idle_cpu_init() and intel_idle_cpuidle_driver_init(),
> they are having the same for(;;) loop.
>
> Here in intel_idle_cpu_init(), the dev->state_count can be assigned by
> drv->state_count directly.
>
> Signed-off-by: liu chuansheng <chuansheng.liu@xxxxxxxxx>
> ---
> drivers/idle/intel_idle.c | 30 ++----------------------------
> 1 files changed, 2 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index 17c9cf9..503b401 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -599,38 +599,12 @@ static int intel_idle_cpuidle_driver_init(void)
> */
> static int intel_idle_cpu_init(int cpu)
> {
> - int cstate;
> struct cpuidle_device *dev;
> + struct cpuidle_driver *drv = &intel_idle_driver;
>
> dev = per_cpu_ptr(intel_idle_cpuidle_devices, cpu);
>
> - dev->state_count = 1;
> -
> - for (cstate = 0; cstate < CPUIDLE_STATE_MAX; ++cstate) {
> - int num_substates, mwait_hint, mwait_cstate, mwait_substate;
> -
> - if (cpuidle_state_table[cstate].enter == NULL)
> - break;
> -
> - if (cstate + 1 > max_cstate) {
> - printk(PREFIX "max_cstate %d reached\n", max_cstate);
> - break;
> - }
> -
> - mwait_hint = flg2MWAIT(cpuidle_state_table[cstate].flags);
> - mwait_cstate = MWAIT_HINT2CSTATE(mwait_hint);
> - mwait_substate = MWAIT_HINT2SUBSTATE(mwait_hint);
> -
> - /* does the state exist in CPUID.MWAIT? */
> - num_substates = (mwait_substates >> ((mwait_cstate + 1) * 4))
> - & MWAIT_SUBSTATE_MASK;
> -
> - /* if sub-state in table is not enumerated by CPUID */
> - if ((mwait_substate + 1) > num_substates)
> - continue;
> -
> - dev->state_count += 1;
> - }
> + dev->state_count = drv->state_count;

The cpuidle_register_device function already does this initialization.

Probably you can get rid of this initialization and certainly factor out
a bit the code in this case.


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