linux-kernel - Re: [PATCH RFC] davinci: poll for sleep completion in resume routine.

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Message-ID: <511C65B3.7060109@ti.com>
Date:	Thu, 14 Feb 2013 09:48:59 +0530
From:	Sekhar Nori <nsekhar@...com>
To:	"Vishwanathrao Badarkhe, Manish" <manishv.b@...com>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<davinci-linux-open-source@...ux.davincidsp.com>,
	<linux-kernel@...r.kernel.org>, <linux@....linux.org.uk>,
	<khilman@...prootsystems.com>
Subject: Re: [PATCH RFC] davinci: poll for sleep completion in resume routine.

Manish,

On 1/31/2013 2:56 PM, Vishwanathrao Badarkhe, Manish wrote:
> As per OMAP-L138 TRM, Software must poll for
> SLEEPCOMPLETE bit until it is set to 1 before clearing
> SLEEPENABLE bit in DEEPSLEEP register in resume routine.
> Modifications are as per datasheet:
> http://www.ti.com/lit/ug/spruh77a/spruh77a.pdf
> See sections 10.10.2.2 and 11.5.21 for more detailed
> explanation.

Polling for SLEEPCOMPLETE is not required in RTC controlled wake-up
which is the mode currently supported (see section 10.10.2.1 of the
TRM). Polling for SLEEPCOMPLETE is required for external controlled
wake-up which to my knowledge has never been tested. If you have tested
this with external controlled wakep-up, then I can consider this patch.
Else, I would like to take it only after externally controlled wake-up
is fully tested/supported instead of taking bits and pieces.

Thanks,
Sekhar

> 
> Tested on da850-evm.
> 
> Signed-off-by: Vishwanathrao Badarkhe, Manish <manishv.b@...com>
> ---
> :100644 100644 d4e9316... 976f096... M	arch/arm/mach-davinci/sleep.S
>  arch/arm/mach-davinci/sleep.S |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/mach-davinci/sleep.S b/arch/arm/mach-davinci/sleep.S
> index d4e9316..976f096 100644
> --- a/arch/arm/mach-davinci/sleep.S
> +++ b/arch/arm/mach-davinci/sleep.S
> @@ -35,6 +35,7 @@
>  #define PLL_LOCK_CYCLES		(PLL_LOCK_TIME * 25)
>  
>  #define DEEPSLEEP_SLEEPENABLE_BIT	BIT(31)
> +#define DEEPSLEEP_SLEEPCOMPLETE_BIT 	BIT(30)
>  
>  	.text
>  /*
> @@ -110,6 +111,13 @@ ENTRY(davinci_cpu_suspend)
>  
>  	/* Wake up from sleep */
>  
> +	/* wait for sleep complete */
> +sleep_complete:
> +	ldr 	ip, [r4]
> +	and 	ip, ip, #DEEPSLEEP_SLEEPCOMPLETE_BIT
> +	cmp 	ip, #DEEPSLEEP_SLEEPCOMPLETE_BIT
> +	bne 	sleep_complete
> +
>  	/* Clear sleep enable */
>  	ldr	ip, [r4]
>  	bic	ip, ip, #DEEPSLEEP_SLEEPENABLE_BIT
> 
--
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