Re: [PATCHv2 1/1] omap3: cpuidle: Update statistics for correct state

[Kevin Hilman <khilman@deeprootsystems.com>]

Sanjeev Premi <premi@ti.com> writes:

> When 'enable_off_mode' is 0, the target power state for MPU
> and CORE was locally changed to PWRDM_POWER_RET but, the
> statistics are updated for idle state originally selected
> by the governor.
>
> This patch 'invalidates' the idle states that lead either of
> MPU or Core to PWRDM_POWER_OFF state when 'enable_off_mode'
> is '0'. The states are valid once 'enable_off_mode' is set
> to '1'.
>
> Added function next_valid_state() to check if current state
> is valid; else get the next valid state. It is called from
> omap3_enter_idle_bm().
>
> Signed-off-by: Sanjeev Premi <premi@ti.com>

Hi Sanjeev,

I quite like this approach, but have a few minor comments.  First,
please fix the checkpatch errors and warnings, as well as a few minor
things below...

> ---
>  arch/arm/mach-omap2/cpuidle34xx.c |   98 ++++++++++++++++++++++++++++++++++---
>  arch/arm/mach-omap2/pm.h          |    1 +
>  arch/arm/mach-omap2/pm34xx.c      |    4 ++
>  3 files changed, 95 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c
> index fdfa1d5..308865c 100644
> --- a/arch/arm/mach-omap2/cpuidle34xx.c
> +++ b/arch/arm/mach-omap2/cpuidle34xx.c
> @@ -45,6 +45,8 @@
>  #define OMAP3_STATE_C6 5 /* C6 - MPU OFF + Core RET */
>  #define OMAP3_STATE_C7 6 /* C7 - MPU OFF + Core OFF */
>  
> +#define OMAP3_STATE_MAX OMAP3_STATE_C7
> +
>  struct omap3_processor_cx {
>  	u8 valid;
>  	u8 type;
> @@ -128,13 +130,6 @@ static int omap3_enter_idle(struct cpuidle_device *dev,
>  	local_irq_disable();
>  	local_fiq_disable();
>  
> -	if (!enable_off_mode) {
> -		if (mpu_state < PWRDM_POWER_RET)
> -			mpu_state = PWRDM_POWER_RET;
> -		if (core_state < PWRDM_POWER_RET)
> -			core_state = PWRDM_POWER_RET;
> -	}
> -
>  	pwrdm_set_next_pwrst(mpu_pd, mpu_state);
>  	pwrdm_set_next_pwrst(core_pd, core_state);
>  
> @@ -164,6 +159,65 @@ return_sleep_time:
>  	return (u32)timespec_to_ns(&ts_idle)/1000;
>  }
>  
> +
> +/* next_valid_state - Find next valid c-state
> + * @dev: cpuidle device
> + * @state: Currently selected c-state
> + *
> + * If the current state is valid, it is returned back to the caller.
> + * Else, this function searches for a lower c-state which is still
> + * valid (as defined in omap3_power_states[]).
> + */

Please fix kerneldoc style.   Opening comment should be '/**'

> +static struct cpuidle_state* next_valid_state(struct cpuidle_device *dev,
> +						struct cpuidle_state *curr)
> +{
> +	struct cpuidle_state *next = NULL;
> +	struct omap3_processor_cx *cx;
> +
> +	cx = (struct omap3_processor_cx *)cpuidle_get_statedata(curr);
> +
> +	/* Check if current state is valid */
> +	if (cx->valid) {
> +		next = curr;

could just return curr here

> +	}
> +	else {
> +		u8 idx = OMAP3_STATE_MAX;
> +
> +		/* Reach the current state starting at highest C-state */
> +		for (; idx >= OMAP3_STATE_C1; idx--) {
> +			if (&dev->states[idx] == curr) {
> +				next = &dev->states[idx];
> +				break;
> +			}
> +		}
> +
> +		/*
> +		 * Should never hit this condition.
> +		 */
> +		BUG_ON(next == NULL);

This shouldn't trigger a panic.  Please fail more cleanly using WARN_ON()

> +		/* Drop to next valid state.
> +		 * Start search from the next (lower) state.
> +		 */

fix multiline comment.  Should start with '/*' on its own line.
(c.f. Documentation/CodingStyle, search for 'multi-line')

> +		idx--;
> +		for (; idx >= OMAP3_STATE_C1; idx--) {
> +			if (((struct omap3_processor_cx *)
> +				cpuidle_get_statedata(
> +					&dev->states[idx]))->valid) {
> +				next = &dev->states[idx];
> +				break;
> +			}
> +		}

Due to line-wrapping etc., this has readabiliyt problems.  Consider this
instead:

		for (; idx >= OMAP3_STATE_C1; idx--) {
			struct omap3_processor_cx *cx;

			cx = cpuidle_get_statedata(&dev->states[idx]);
			if (cx->valid) {
				next = &dev->states[idx];
				break;
			}
		}

> +		/*
> +		 * C1 and C2 are always valid.
> +		 * So, no need to check for 'next==NULL' outside this loop.
> +		 */
> +	}
> +
> +	return next;
> +}
> +
> +
>  /**
>   * omap3_enter_idle_bm - Checks for any bus activity
>   * @dev: cpuidle device
> @@ -176,7 +230,7 @@ return_sleep_time:
>  static int omap3_enter_idle_bm(struct cpuidle_device *dev,
>  			       struct cpuidle_state *state)
>  {
> -	struct cpuidle_state *new_state = state;
> +	struct cpuidle_state *new_state= next_valid_state(dev, state);
                                       ^

missing space

>  
>  	if ((state->flags & CPUIDLE_FLAG_CHECK_BM) && omap3_idle_bm_check()) {
>  		BUG_ON(!dev->safe_state);
> @@ -207,6 +261,32 @@ void omap3_pm_init_cpuidle(struct cpuidle_params *cpuidle_board_params)
>  	return;
>  }
>  
> +/**
> + * omap3_cpuidle_update_states - Update the cpuidle states.
> + *
> + * Currently, this function toggles the validity of idle states based upon
> + * the flag 'enable_off_mode'. When the flag is set all states are valid.
> + * Else, states leading to OFF state set to be invalid.
> + */
> +void omap3_cpuidle_update_states(void)
> +{
> +	int i;
> +
> +	for (i = OMAP3_STATE_C1; i < OMAP3_MAX_STATES; i++) {
> +		if (enable_off_mode) {
> +			omap3_power_states[i].valid = 1;
> +		}
> +		else {
> +			if ((omap3_power_states[i].mpu_state
> +					== PWRDM_POWER_OFF)
> +				|| (omap3_power_states[i].core_state
> +					== PWRDM_POWER_OFF))
> +			omap3_power_states[i].valid = 0;
> +		}
> +	}
> +}

more readability problems due to wrapping.  consider:

void omap3_cpuidle_update_states(void)
{
	int i;

	for (i = OMAP3_STATE_C1; i < OMAP3_MAX_STATES; i++) {
		struct omap3_processor_cx *cx = &omap3_power_states[i]

		if (enable_off_mode)
			cx->valid = 1;
		else
			if ((cx->mpu_state == PWRDM_POWER_OFF) ||
			    (cx->core_state == PWRDM_POWER_OFF))
				cx->valid = 0;
	}
}

Kevin


> +
>  /* omap3_init_power_states - Initialises the OMAP3 specific C states.
>   *
>   * Below is the desciption of each C state.
> @@ -365,6 +445,8 @@ int __init omap3_idle_init(void)
>  		return -EINVAL;
>  	dev->state_count = count;
>  
> +	omap3_cpuidle_update_states();
> +
>  	if (cpuidle_register_device(dev)) {
>  		printk(KERN_ERR "%s: CPUidle register device failed\n",
>  		       __func__);
> diff --git a/arch/arm/mach-omap2/pm.h b/arch/arm/mach-omap2/pm.h
> index b9421e8..9351490 100644
> --- a/arch/arm/mach-omap2/pm.h
> +++ b/arch/arm/mach-omap2/pm.h
> @@ -51,6 +51,7 @@ struct cpuidle_params {
>  extern void omap3_pm_init_vc(struct prm_setup_vc *setup_vc);
>  #ifdef CONFIG_CPU_IDLE
>  extern void omap3_pm_init_cpuidle(struct cpuidle_params *cpuidle_board_params);
> +extern void omap3_cpuidle_update_states(void);
>  #else
>  static inline void omap3_pm_init_cpuidle(
>  			struct cpuidle_params *cpuidle_board_params)
> diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
> index 90c4949..d9f0626 100644
> --- a/arch/arm/mach-omap2/pm34xx.c
> +++ b/arch/arm/mach-omap2/pm34xx.c
> @@ -981,6 +981,10 @@ void omap3_pm_off_mode_enable(int enable)
>  	else
>  		state = PWRDM_POWER_RET;
>  
> +#ifdef CONFIG_CPU_IDLE
> +	omap3_cpuidle_update_states();
> +#endif
> +
>  #ifdef CONFIG_OMAP_PM_SRF
>  	resource_lock_opp(VDD1_OPP);
>  	resource_lock_opp(VDD2_OPP);
> -- 
> 1.6.2.2
>
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