linux-kernel - Re: [RFC v2 1/1] clk: Add notifier support in clk_prepare/clk

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Date:	Thu, 14 Mar 2013 02:51:27 -0700
From:	Bill Huang <bilhuang@...dia.com>
To:	"mturquette@...aro.org" <mturquette@...aro.org>
CC:	"patches@...aro.org" <patches@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-dev@...ts.linaro.org" <linaro-dev@...ts.linaro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC v2 1/1] clk: Add notifier support in
 clk_prepare/clk_unprepare

On Thu, 2013-03-14 at 17:31 +0800, Bill Huang wrote:
> Add the below two notifier events so drivers which are interested in
> knowing the clock status can act accordingly. This is extremely useful
> in some of the DVFS (Dynamic Voltage Frequency Scaling) design.
> 
> CLK_PREPARED
> CLK_UNPREPARED
> 
> Signed-off-by: Bill Huang <bilhuang@...dia.com>
> ---
>  drivers/clk/clk.c   |    3 +++
>  include/linux/clk.h |    2 ++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index ed87b24..3292cec 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -550,6 +550,7 @@ void clk_unprepare(struct clk *clk)
>  {
>  	mutex_lock(&prepare_lock);
>  	__clk_unprepare(clk);
> +	__clk_notify(clk, CLK_UNPREPARED, clk->rate, clk->rate);
>  	mutex_unlock(&prepare_lock);
>  }
>  EXPORT_SYMBOL_GPL(clk_unprepare);
> @@ -598,6 +599,8 @@ int clk_prepare(struct clk *clk)
>  
>  	mutex_lock(&prepare_lock);
>  	ret = __clk_prepare(clk);
> +	if (!ret)
> +		__clk_notify(clk, CLK_PREPARED, clk->rate, clk->rate);
>  	mutex_unlock(&prepare_lock);
>  
>  	return ret;
> diff --git a/include/linux/clk.h b/include/linux/clk.h
> index b3ac22d..16c1d92 100644
> --- a/include/linux/clk.h
> +++ b/include/linux/clk.h
> @@ -43,6 +43,8 @@ struct clk;
>  #define PRE_RATE_CHANGE			BIT(0)
>  #define POST_RATE_CHANGE		BIT(1)
>  #define ABORT_RATE_CHANGE		BIT(2)
> +#define CLK_PREPARED			BIT(3)
> +#define CLK_UNPREPARED			BIT(4)
>  
>  /**
>   * struct clk_notifier - associate a clk with a notifier
Sorry, I'll send v3 since this bread build.


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