Re: [PATCH 1/5] OMAP4: PM: Use the lowpwrstatechange feature on OMAP4

[Kevin Hilman <khilman@deeprootsystems.com>]

Rajendra Nayak <rnayak@ti.com> writes:

> Hi Kevin,
>
> <snip>..
>
>> >  	if (pwrdm_read_pwrst(pwrdm) < PWRDM_POWER_ON) {
>> > +		if ((pwrdm_read_pwrst(pwrdm) > state) &&
>> > +			(pwrdm->flags & PWRDM_HAS_LOWPOWERSTATECHANGE)) {
>> > +				ret = pwrdm_set_next_pwrst(pwrdm, state);
>> > +				pwrdm_set_lowpwrstchange(pwrdm);
>> > +				pwrdm_wait_transition(pwrdm);
>> > +				pwrdm_state_switch(pwrdm);
>> > +				return ret;
>>
>> Personally, I'd prefer if this function flowed through better instead of
>> the early return in order to emphasize the common code.
>>
>> Rather than the return here, can you just set the low-power state change
>> bit here (and put the clkdm_wakeup + sleep_switch = 1 into the else
>> clause?
>>
>> Or, does the next state have to be set before the low-power state change
>> bit?
>
> Yes, that sequencing is needed.
>
>>
>> Basically, what I'm getting at is this should be a single function with
>> common flow.  The conditional code based on low-power state change
>> should be isolated instead of having a special path.
>
> I get your point. See if the below approach looks better.
> If it looks fine, I'll do some more testing (currently only tested
> on OMAP4430sdp) and repost the 2 patches.

Yes, this approach leads to better readability IMO.

Thanks,

Kevin

> From 5d206ba908071edafae6c044bd3ef6ad8a9c32e7 Mon Sep 17 00:00:00 2001
> From: Rajendra Nayak <rnayak@ti.com>
> Date: Thu, 25 Nov 2010 14:26:51 +0530
> Subject: [PATCH 1/5] OMAP4: PM: Use the low-power state change feature on
> OMAP4
>
> For pwrdm's which support LOWPOWERSTATECHANGE, do not try waking
> up the domain to put it back to deeper sleep state.
>
> Signed-off-by: Rajendra Nayak <rnayak@ti.com>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
> Acked-by: Benoit Cousson <b-cousson@ti.com>
> ---
>  arch/arm/mach-omap2/pm.c |   28 ++++++++++++++++++++++------
>  1 file changed, 22 insertions(+), 6 deletions(-)
>
> Index: linux/arch/arm/mach-omap2/pm.c
> ===================================================================
> --- linux.orig/arch/arm/mach-omap2/pm.c	2010-12-15 17:29:42.361228780
> +0530
> +++ linux/arch/arm/mach-omap2/pm.c	2010-12-15 20:19:48.321228780
> +0530
> @@ -89,6 +89,10 @@
>  	}
>  }
>
> +/* Types of sleep_switch used in omap_set_pwrdm_state */
> +#define FORCEWAKEUP_SWITCH	0
> +#define LOWPOWERSTATE_SWITCH	1
> +
>  /*
>   * This sets pwrdm state (other than mpu & core. Currently only ON &
>   * RET are supported. Function is assuming that clkdm doesn't have
> @@ -114,9 +118,14 @@
>  		return ret;
>
>  	if (pwrdm_read_pwrst(pwrdm) < PWRDM_POWER_ON) {
> -		omap2_clkdm_wakeup(pwrdm->pwrdm_clkdms[0]);
> -		sleep_switch = 1;
> -		pwrdm_wait_transition(pwrdm);
> +		if ((pwrdm_read_pwrst(pwrdm) > state) &&
> +			(pwrdm->flags & PWRDM_HAS_LOWPOWERSTATECHANGE)) {
> +			sleep_switch = LOWPOWERSTATE_SWITCH;
> +		} else {
> +			omap2_clkdm_wakeup(pwrdm->pwrdm_clkdms[0]);
> +			pwrdm_wait_transition(pwrdm);
> +			sleep_switch = FORCEWAKEUP_SWITCH;
> +		}
>  	}
>
>  	ret = pwrdm_set_next_pwrst(pwrdm, state);
> @@ -126,12 +135,19 @@
>  		goto err;
>  	}
>
> -	if (sleep_switch) {
> +	switch (sleep_switch) {
> +	case FORCEWAKEUP_SWITCH:
>  		omap2_clkdm_allow_idle(pwrdm->pwrdm_clkdms[0]);
> -		pwrdm_wait_transition(pwrdm);
> -		pwrdm_state_switch(pwrdm);
> +		break;
> +	case LOWPOWERSTATE_SWITCH:
> +		pwrdm_set_lowpwrstchange(pwrdm);
> +		break;
> +	default:
> +		return ret;
>  	}
>
> +	pwrdm_wait_transition(pwrdm);
> +	pwrdm_state_switch(pwrdm);
>  err:
>  	return ret;
>  }
>
>
>>
>> Kevin
>>
>> > +		}
>> >  		omap2_clkdm_wakeup(pwrdm->pwrdm_clkdms[0]);
>> >  		sleep_switch = 1;
>> >  		pwrdm_wait_transition(pwrdm);