Subject: Re: [PATCH 1/2] powerpc/cpuidle: Only clear LPCR decrementer wakeup bit on fast sleep entry

From: Preeti U Murthy <[email-masked]>
Date: Thu, 05 Jun 2014 08:35:38 +0530

On 06/02/2014 12:27 PM, Michael Neuling wrote:
> Currently when entering fastsleep we clear all LPCR PECE bits.
> 
> This patch changes it to only clear the decrementer bit (ie. PECE1), which is
> the only bit we really need to clear here.  This is needed if we want to set
> other wakeup causes like the PECEDH bit so we can use hypervisor doorbells on
> powernv.
> 
> Signed-off-by: Michael Neuling <[email-masked]>
> ---
>  drivers/cpuidle/cpuidle-powernv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
> index 719f6fb..7f7798e 100644
> --- a/drivers/cpuidle/cpuidle-powernv.c
> +++ b/drivers/cpuidle/cpuidle-powernv.c
> @@ -73,7 +73,7 @@ static int fastsleep_loop(struct cpuidle_device *dev,
>  		return index;
>  
>  	new_lpcr = old_lpcr;
> -	new_lpcr &= ~(LPCR_MER | LPCR_PECE); /* lpcr[mer] must be 0 */
> +	new_lpcr &= ~(LPCR_MER | LPCR_PECE1); /* lpcr[mer] must be 0 */
>  
>  	/* exit powersave upon external interrupt, but not decrementer
>  	 * interrupt.
You might want to remove this comment and instead simply add
/* Do not exit powersave upon decrementer interrupt */

Besides this, the following line which clears the wakeup from external
interrupt bit can be removed as well, since we are not clearing it anyway ?

 new_lpcr |= LPCR_PECE0
 ^^^

Regards
Preeti U Murthy