linux-kernel - Re: [PATCH v6 1/1] mfd: arizona: Export functions to control subsystem DVFS

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Message-ID: <20150519152351.GA31187@opensource.wolfsonmicro.com>
Date:	Tue, 19 May 2015 16:23:51 +0100
From:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
To:	Richard Fitzgerald <rf@...nsource.wolfsonmicro.com>
Cc:	lee.jones@...aro.org, broonie@...nel.org,
	linux-kernel@...r.kernel.org, patches@...nsource.wolfsonmicro.com
Subject: Re: [PATCH v6 1/1] mfd: arizona: Export functions to control
	subsystem DVFS

On Tue, May 19, 2015 at 03:57:42PM +0100, Richard Fitzgerald wrote:
> The WM5102, WM8997, WM8998 and WM1814 codecs have an internal dynamic
> clock booster. When this booster is active, the DCVDD voltage must be
> increased. If all the currently active audio paths can run with the root
> SYSCLK we can disable the booster, allowing us to turn down DCVDD voltage
> to save power.
> 
> Previously this was being done by having the booster enable bit set
> as a side-effect of the LDO1 regulator driver, which is unexpected
> behaviour of a regulator and not compatible with using an external
> regulator.
> 
> This patch exports functions to handle the booster enable and
> DCVDD voltage, with each relevant subsystem flagging whether it can
> currently run without the booster. Note that these subsystems are
> stateless and none of them are nestable, so there's no need for
> reference counting, we only need a simple boolean for each subsystem
> of whether their current condition could require the booster or will
> allow us to turn the codec down to lower operating power.
> 
> Signed-off-by: Richard Fitzgerald <rf@...nsource.wolfsonmicro.com>
> ---

Reviewed-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>

Thanks,
Charles
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