linux-kernel - Re: [RFC 1/1] clk: Add notifier support in clk_prepare_enable/clk_disable

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Message-ID: <20130312134032.GU4977@n2100.arm.linux.org.uk>
Date:	Tue, 12 Mar 2013 13:40:32 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Bill Huang <bilhuang@...dia.com>
Cc:	mturquette@...aro.org, linux-kernel@...r.kernel.org,
	linaro-dev@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
	patches@...aro.org
Subject: Re: [RFC 1/1] clk: Add notifier support in
	clk_prepare_enable/clk_disable_unprepare

On Tue, Mar 12, 2013 at 05:37:41AM -0700, Bill Huang wrote:
> Add the below four 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.
> 
> PRE_CLK_ENABLE
> POST_CLK_ENABLE
> PRE_CLK_DISABLE
> POST_CLK_DISABLE
> 
> Signed-off-by: Bill Huang <bilhuang@...dia.com>

NAK.  *Sigh* NO, this is the wrong level to be doing stuff like this.

The *ONLY* thing that clk_prepare_enable() and clk_prepare_disable() should
*EVER* be doing is calling clk_prepare(), clk_enable(), clk_disable() and
clk_unprepare().  Those two functions are *merely* helpers for drivers
who don't wish to make the individual calls.

Drivers are still completely free to call the individual functions, at
which point your proposal breaks horribly - and they _do_ call the
individual functions.
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