RE: [PATCH] Add new lower-latency C1 state take #2

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> -----Original Message-----
> From: linux-omap-owner@xxxxxxxxxxxxxxx 
> [mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of Kevin Hilman
> Sent: Saturday, March 14, 2009 3:38 AM
> To: Peter 'p2' De Schrijver
> Cc: linux-omap@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] Add new lower-latency C1 state take #2
> 
> "Peter 'p2' De Schrijver" <peter.de-schrijver@xxxxxxxxx> writes:
> 
> > This patch introduces a new C state which allows MPU to go 
> to WFI but 
> > keeps the core domain active. This offers a much better 
> wakeup latency 
> > (3us vs 10s of us for the current C1) at the cost of a 
> higher power consumption.
> > Fixed the comments.
> >
> > Signed-off-by: Peter 'p2' De Schrijver 
> <peter.de-schrijver@xxxxxxxxx>
> 
> Thanks, pushing to PM branch.
> 
> Kevin
> 
> > ---
> >  arch/arm/mach-omap2/cpuidle34xx.c |  121 
> > ++++++++++++++++++++++++-------------
> >  1 files changed, 78 insertions(+), 43 deletions(-)
> >
> > diff --git a/arch/arm/mach-omap2/cpuidle34xx.c 
> > b/arch/arm/mach-omap2/cpuidle34xx.c
> > index 62fbb2e..7da2fd8 100644
> > --- a/arch/arm/mach-omap2/cpuidle34xx.c
> > +++ b/arch/arm/mach-omap2/cpuidle34xx.c
> > @@ -26,6 +26,7 @@
> >  #include <mach/pm.h>
> >  #include <mach/prcm.h>
> >  #include <mach/powerdomain.h>
> > +#include <mach/clockdomain.h>
> >  #include <mach/control.h>
> >  #include <mach/serial.h>
> >  
> > @@ -33,13 +34,14 @@
> >  
> >  #ifdef CONFIG_CPU_IDLE
> >  
> > -#define OMAP3_MAX_STATES 7
> > +#define OMAP3_MAX_STATES 8
> >  #define OMAP3_STATE_C1 1 /* C1 - MPU WFI + Core active */ -#define 
> > OMAP3_STATE_C2 2 /* C2 - MPU CSWR + Core active */ -#define 
> > OMAP3_STATE_C3 3 /* C3 - MPU OFF + Core active */ -#define 
> > OMAP3_STATE_C4 4 /* C4 - MPU RET + Core RET */ -#define 
> OMAP3_STATE_C5 
> > 5 /* C5 - MPU OFF + Core RET */ -#define OMAP3_STATE_C6 6 
> /* C6 - MPU 
> > OFF + Core OFF */
> > +#define OMAP3_STATE_C2 2 /* C2 - MPU WFI + Core inactive 
> */ #define 
> > +OMAP3_STATE_C3 3 /* C3 - MPU CSWR + Core inactive */ #define 
> > +OMAP3_STATE_C4 4 /* C4 - MPU OFF + Core iactive */ #define 
> > +OMAP3_STATE_C5 5 /* C5 - MPU RET + Core RET */ #define 
> OMAP3_STATE_C6 
> > +6 /* C6 - MPU OFF + Core RET */ #define OMAP3_STATE_C7 7 
> /* C7 - MPU 
> > +OFF + Core OFF */
> >  
> >  struct omap3_processor_cx {
> >  	u8 valid;
> > @@ -63,6 +65,18 @@ static int omap3_idle_bm_check(void)
> >  	return 0;
> >  }
> >  
> > +static int _cpuidle_allow_idle(struct powerdomain *pwrdm,
> > +				struct clockdomain *clkdm)
> > +{
> > +	omap2_clkdm_allow_idle(clkdm);
> > +}
> > +
> > +static int _cpuidle_deny_idle(struct powerdomain *pwrdm,
> > +				struct clockdomain *clkdm)
> > +{
> > +	omap2_clkdm_deny_idle(clkdm);
> > +}
> > +

These functions don't return any value. Even the functions 
omap2_clkdm_allow_idle() and omap2_clkdm_deny_idle() are
void.

So, the return type should be changed to void. Else complier
would throw warnings like:

warning: no return statement in function returning non-void

~sanjeev

> >  /**
> >   * omap3_enter_idle - Programs OMAP3 to enter the specified state
> >   * @dev: cpuidle device
> > @@ -99,9 +113,19 @@ static int omap3_enter_idle(struct 
> cpuidle_device *dev,
> >  	if (omap_irq_pending())
> >  		goto return_sleep_time;
> >  
> > +	if (cx->type == OMAP3_STATE_C1) {
> > +		pwrdm_for_each_clkdm(mpu_pd, _cpuidle_deny_idle);
> > +		pwrdm_for_each_clkdm(core_pd, _cpuidle_deny_idle);
> > +	}
> > +
> >  	/* Execute ARM wfi */
> >  	omap_sram_idle();
> >  
> > +	if (cx->type == OMAP3_STATE_C1) {
> > +		pwrdm_for_each_clkdm(mpu_pd, _cpuidle_allow_idle);
> > +		pwrdm_for_each_clkdm(core_pd, _cpuidle_allow_idle);
> > +	}
> > +
> >  return_sleep_time:
> >  	getnstimeofday(&ts_postidle);
> >  	ts_idle = timespec_sub(ts_postidle, ts_preidle); @@ 
> -140,79 +164,90 
> > @@ DEFINE_PER_CPU(struct cpuidle_device, omap3_idle_dev);
> >  /* omap3_init_power_states - Initialises the OMAP3 
> specific C states.
> >   *
> >   * Below is the desciption of each C state.
> > - *	C1 . MPU WFI + Core active
> > - *	C2 . MPU CSWR + Core active
> > - *	C3 . MPU OFF + Core active
> > - *	C4 . MPU CSWR + Core CSWR
> > - *	C5 . MPU OFF + Core CSWR
> > - *	C6 . MPU OFF + Core OFF
> > + * 	C1 . MPU WFI + Core active
> > + *	C2 . MPU WFI + Core inactive
> > + *	C3 . MPU CSWR + Core inactive
> > + *	C4 . MPU OFF + Core inactive
> > + *	C5 . MPU CSWR + Core CSWR
> > + *	C6 . MPU OFF + Core CSWR
> > + *	C7 . MPU OFF + Core OFF
> >   */
> >  void omap_init_power_states(void)
> >  {
> >  	/* C1 . MPU WFI + Core active */
> >  	omap3_power_states[OMAP3_STATE_C1].valid = 1;
> >  	omap3_power_states[OMAP3_STATE_C1].type = OMAP3_STATE_C1;
> > -	omap3_power_states[OMAP3_STATE_C1].sleep_latency = 10;
> > -	omap3_power_states[OMAP3_STATE_C1].wakeup_latency = 10;
> > -	omap3_power_states[OMAP3_STATE_C1].threshold = 30;
> > +	omap3_power_states[OMAP3_STATE_C1].sleep_latency = 2;
> > +	omap3_power_states[OMAP3_STATE_C1].wakeup_latency = 2;
> > +	omap3_power_states[OMAP3_STATE_C1].threshold = 5;
> >  	omap3_power_states[OMAP3_STATE_C1].mpu_state = PWRDM_POWER_ON;
> >  	omap3_power_states[OMAP3_STATE_C1].core_state = PWRDM_POWER_ON;
> >  	omap3_power_states[OMAP3_STATE_C1].flags = 
> CPUIDLE_FLAG_TIME_VALID;
> >  
> > -	/* C2 . MPU CSWR + Core active */
> > +	/* C2 . MPU WFI + Core inactive */
> >  	omap3_power_states[OMAP3_STATE_C2].valid = 1;
> >  	omap3_power_states[OMAP3_STATE_C2].type = OMAP3_STATE_C2;
> > -	omap3_power_states[OMAP3_STATE_C2].sleep_latency = 50;
> > -	omap3_power_states[OMAP3_STATE_C2].wakeup_latency = 50;
> > -	omap3_power_states[OMAP3_STATE_C2].threshold = 300;
> > -	omap3_power_states[OMAP3_STATE_C2].mpu_state = PWRDM_POWER_RET;
> > +	omap3_power_states[OMAP3_STATE_C2].sleep_latency = 10;
> > +	omap3_power_states[OMAP3_STATE_C2].wakeup_latency = 10;
> > +	omap3_power_states[OMAP3_STATE_C2].threshold = 30;
> > +	omap3_power_states[OMAP3_STATE_C2].mpu_state = PWRDM_POWER_ON;
> >  	omap3_power_states[OMAP3_STATE_C2].core_state = PWRDM_POWER_ON;
> > -	omap3_power_states[OMAP3_STATE_C2].flags = 
> CPUIDLE_FLAG_TIME_VALID |
> > -				CPUIDLE_FLAG_CHECK_BM;
> > +	omap3_power_states[OMAP3_STATE_C2].flags = 
> CPUIDLE_FLAG_TIME_VALID;
> >  
> > -	/* C3 . MPU OFF + Core active */
> > +	/* C3 . MPU CSWR + Core inactive */
> >  	omap3_power_states[OMAP3_STATE_C3].valid = 1;
> >  	omap3_power_states[OMAP3_STATE_C3].type = OMAP3_STATE_C3;
> > -	omap3_power_states[OMAP3_STATE_C3].sleep_latency = 1500;
> > -	omap3_power_states[OMAP3_STATE_C3].wakeup_latency = 1800;
> > -	omap3_power_states[OMAP3_STATE_C3].threshold = 4000;
> > -	omap3_power_states[OMAP3_STATE_C3].mpu_state = PWRDM_POWER_OFF;
> > +	omap3_power_states[OMAP3_STATE_C3].sleep_latency = 50;
> > +	omap3_power_states[OMAP3_STATE_C3].wakeup_latency = 50;
> > +	omap3_power_states[OMAP3_STATE_C3].threshold = 300;
> > +	omap3_power_states[OMAP3_STATE_C3].mpu_state = PWRDM_POWER_RET;
> >  	omap3_power_states[OMAP3_STATE_C3].core_state = PWRDM_POWER_ON;
> >  	omap3_power_states[OMAP3_STATE_C3].flags = 
> CPUIDLE_FLAG_TIME_VALID |
> >  				CPUIDLE_FLAG_CHECK_BM;
> >  
> > -	/* C4 . MPU CSWR + Core CSWR*/
> > +	/* C4 . MPU OFF + Core inactive */
> >  	omap3_power_states[OMAP3_STATE_C4].valid = 1;
> >  	omap3_power_states[OMAP3_STATE_C4].type = OMAP3_STATE_C4;
> > -	omap3_power_states[OMAP3_STATE_C4].sleep_latency = 2500;
> > -	omap3_power_states[OMAP3_STATE_C4].wakeup_latency = 7500;
> > -	omap3_power_states[OMAP3_STATE_C4].threshold = 12000;
> > -	omap3_power_states[OMAP3_STATE_C4].mpu_state = PWRDM_POWER_RET;
> > -	omap3_power_states[OMAP3_STATE_C4].core_state = PWRDM_POWER_RET;
> > +	omap3_power_states[OMAP3_STATE_C4].sleep_latency = 1500;
> > +	omap3_power_states[OMAP3_STATE_C4].wakeup_latency = 1800;
> > +	omap3_power_states[OMAP3_STATE_C4].threshold = 4000;
> > +	omap3_power_states[OMAP3_STATE_C4].mpu_state = PWRDM_POWER_OFF;
> > +	omap3_power_states[OMAP3_STATE_C4].core_state = PWRDM_POWER_ON;
> >  	omap3_power_states[OMAP3_STATE_C4].flags = 
> CPUIDLE_FLAG_TIME_VALID |
> >  				CPUIDLE_FLAG_CHECK_BM;
> >  
> > -	/* C5 . MPU OFF + Core CSWR */
> > +	/* C5 . MPU CSWR + Core CSWR*/
> >  	omap3_power_states[OMAP3_STATE_C5].valid = 1;
> >  	omap3_power_states[OMAP3_STATE_C5].type = OMAP3_STATE_C5;
> > -	omap3_power_states[OMAP3_STATE_C5].sleep_latency = 3000;
> > -	omap3_power_states[OMAP3_STATE_C5].wakeup_latency = 8500;
> > -	omap3_power_states[OMAP3_STATE_C5].threshold = 15000;
> > -	omap3_power_states[OMAP3_STATE_C5].mpu_state = PWRDM_POWER_OFF;
> > +	omap3_power_states[OMAP3_STATE_C5].sleep_latency = 2500;
> > +	omap3_power_states[OMAP3_STATE_C5].wakeup_latency = 7500;
> > +	omap3_power_states[OMAP3_STATE_C5].threshold = 12000;
> > +	omap3_power_states[OMAP3_STATE_C5].mpu_state = PWRDM_POWER_RET;
> >  	omap3_power_states[OMAP3_STATE_C5].core_state = PWRDM_POWER_RET;
> >  	omap3_power_states[OMAP3_STATE_C5].flags = 
> CPUIDLE_FLAG_TIME_VALID |
> >  				CPUIDLE_FLAG_CHECK_BM;
> >  
> > -	/* C6 . MPU OFF + Core OFF */
> > +	/* C6 . MPU OFF + Core CSWR */
> >  	omap3_power_states[OMAP3_STATE_C6].valid = 1;
> >  	omap3_power_states[OMAP3_STATE_C6].type = OMAP3_STATE_C6;
> > -	omap3_power_states[OMAP3_STATE_C6].sleep_latency = 10000;
> > -	omap3_power_states[OMAP3_STATE_C6].wakeup_latency = 30000;
> > -	omap3_power_states[OMAP3_STATE_C6].threshold = 300000;
> > +	omap3_power_states[OMAP3_STATE_C6].sleep_latency = 3000;
> > +	omap3_power_states[OMAP3_STATE_C6].wakeup_latency = 8500;
> > +	omap3_power_states[OMAP3_STATE_C6].threshold = 15000;
> >  	omap3_power_states[OMAP3_STATE_C6].mpu_state = PWRDM_POWER_OFF;
> > -	omap3_power_states[OMAP3_STATE_C6].core_state = PWRDM_POWER_OFF;
> > +	omap3_power_states[OMAP3_STATE_C6].core_state = PWRDM_POWER_RET;
> >  	omap3_power_states[OMAP3_STATE_C6].flags = 
> CPUIDLE_FLAG_TIME_VALID |
> >  				CPUIDLE_FLAG_CHECK_BM;
> > +
> > +	/* C7 . MPU OFF + Core OFF */
> > +	omap3_power_states[OMAP3_STATE_C7].valid = 1;
> > +	omap3_power_states[OMAP3_STATE_C7].type = OMAP3_STATE_C7;
> > +	omap3_power_states[OMAP3_STATE_C7].sleep_latency = 10000;
> > +	omap3_power_states[OMAP3_STATE_C7].wakeup_latency = 30000;
> > +	omap3_power_states[OMAP3_STATE_C7].threshold = 300000;
> > +	omap3_power_states[OMAP3_STATE_C7].mpu_state = PWRDM_POWER_OFF;
> > +	omap3_power_states[OMAP3_STATE_C7].core_state = PWRDM_POWER_OFF;
> > +	omap3_power_states[OMAP3_STATE_C7].flags = 
> CPUIDLE_FLAG_TIME_VALID |
> > +				CPUIDLE_FLAG_CHECK_BM;
> >  }
> >  
> >  struct cpuidle_driver omap3_idle_driver = {
> > --
> > 1.5.6.3
> >
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