linux-kernel - Re: [PATCH] PM: Hide OPP configuration when SoCs do not provide an implementation

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Date:	Tue, 09 Nov 2010 13:04:17 -0600
From:	Nishanth Menon <nm@...com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	patches@...nsource.wolfsonmicro.com
Subject: Re: [PATCH] PM: Hide OPP configuration when SoCs do not provide an
 implementation

Mark Brown had written, on 11/09/2010 12:24 PM, the following:
> Since the OPP API is only useful with an appropraite SoC-specific
> implementation there is no point in offering the ability to enable
> the API on general systems. Provide an ARCH_HAS OPP Kconfig symbol
> which masks out the option unless selected by an implementation.
Thanks. yep, this is a good change to have.

> 
> Signed-off-by: Mark Brown <broonie@...nsource.wolfsonmicro.com>

Acked-by: Nishanth Menon <nm@...com>

> ---
>  Documentation/power/opp.txt |    3 +++
>  kernel/power/Kconfig        |    4 ++++
>  2 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/power/opp.txt b/Documentation/power/opp.txt
> index 44d87ad..cd44558 100644
> --- a/Documentation/power/opp.txt
> +++ b/Documentation/power/opp.txt
> @@ -37,6 +37,9 @@ Typical usage of the OPP library is as follows:
>  SoC framework	-> modifies on required cases certain OPPs	-> OPP layer
>  		-> queries to search/retrieve information	->
>  
> +Architectures that provide a SoC framework for OPP should select ARCH_HAS_OPP
> +to make the OPP layer available.
> +
>  OPP layer expects each domain to be represented by a unique device pointer. SoC
>  framework registers a set of initial OPPs per device with the OPP layer. This
>  list is expected to be an optimally small number typically around 5 per device.
> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> index 29bff61..a5aff3e 100644
> --- a/kernel/power/Kconfig
> +++ b/kernel/power/Kconfig
> @@ -246,9 +246,13 @@ config PM_OPS
>  	depends on PM_SLEEP || PM_RUNTIME
>  	default y
>  
> +config ARCH_HAS_OPP
> +	bool
> +
>  config PM_OPP
>  	bool "Operating Performance Point (OPP) Layer library"
>  	depends on PM
> +	depends on ARCH_HAS_OPP
>  	---help---
>  	  SOCs have a standard set of tuples consisting of frequency and
>  	  voltage pairs that the device will support per voltage domain. This


-- 
Regards,
Nishanth Menon
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