linux-kernel - Re: [PATCH 1/3] CLK: uninline clk_prepare() and clk

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Date:	Thu, 22 Nov 2012 10:03:53 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Viresh Kumar <viresh.kumar@...aro.org>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Mike Turquette <mturquette@...com>
Subject: Re: [PATCH 1/3] CLK: uninline clk_prepare() and clk_unprepare()

On Thu, Nov 22, 2012 at 09:30:33AM +0000, Russell King - ARM Linux wrote:
> On Wed, Nov 21, 2012 at 06:17:50PM -0800, Dmitry Torokhov wrote:
> > > You've checked non-ARM architectures too?
> > 
> > Yes:
> > 
> > [dtor@...r-d630 linux-next]$ grep -r HAVE_CLK_PREPARE .
> > ./arch/arm/Kconfig:     select HAVE_CLK_PREPARE
> > Binary file ./.git/objects/pack/pack-7dad5ee164f601f1327dc78648fa317772c2d872.pack matches
> > ./include/linux/clk.h:#ifdef CONFIG_HAVE_CLK_PREPARE
> > ./include/linux/clk.h:#ifdef CONFIG_HAVE_CLK_PREPARE
> > ./drivers/clk/Kconfig:config HAVE_CLK_PREPARE
> > ./drivers/clk/Kconfig:  select HAVE_CLK_PREPARE
> 
> Err, no you haven't, not with that grep.  What you've found are the places
> which enable this, and say "yes, I have clk_prepare".
> 
> What HAVE_CLK_PREPARE is about though is providing a transition path between
> drivers using clk_prepare() to platforms which _don't_ have a clk_prepare()
> implementation - and when it's unset, it provides a default implementation.
> 
> So, finding all those places where the symbol exists is the exact opposite
> of what you need to be doing.  You need to find those platforms which have
> CLK support, but which don't have HAVE_CLK_PREPARE selected.

Right, according to my greps under arch/arm, the following define a
clk_enable() function but do not define a clk_prepare() function:

arch/arm/mach-w90x900/clock.c
arch/arm/mach-ep93xx/clock.c
arch/arm/plat-omap/clock.c
arch/arm/plat-samsung/clock.c
arch/arm/mach-lpc32xx/clock.c
arch/arm/mach-msm/clock.c
arch/arm/mach-mmp/clock.c
arch/arm/mach-sa1100/clock.c
arch/arm/mach-at91/clock.c
arch/arm/mach-at91/at91x40.c
arch/arm/mach-pxa/clock.c
arch/arm/plat-versatile/clock.c
arch/arm/mach-davinci/clock.c

This list gets over twice as big if you widen the search to the arch/
subtree.

If any of these makes use of a driver which makes a call to clk_prepare(),
removing HAVE_CLK_PREPARE will break all those platforms.
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