linux-kernel - Re: [PATCH] clk.h: Fix shim ifdef guard (HAVE_CLK -> COMMON

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Message-ID: <20120827185248.GE25321@flint.arm.linux.org.uk>
Date:	Mon, 27 Aug 2012 19:52:48 +0100
From:	Russell King <rmk@....linux.org.uk>
To:	Jeff Mahoney <jeffm@...e.com>
Cc:	Linux Kernel Maling List <linux-kernel@...r.kernel.org>,
	Viresh Kumar <viresh.kumar@...com>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jeff Garzik <jgarzik@...hat.com>, Andrew Lunn <andrew@...n.ch>,
	Bhupesh Sharma <bhupesh.sharma@...com>,
	Giuseppe Cavallaro <peppe.cavallaro@...com>,
	Mike Turquette <mturquette@...aro.org>,
	Sergei Shtylyov <sshtylyov@...mvista.com>
Subject: Re: [PATCH] clk.h: Fix shim ifdef guard (HAVE_CLK -> COMMON_CLK)

On Mon, Aug 27, 2012 at 11:28:15AM -0400, Jeff Mahoney wrote:
> Commit 93abe8e4 (clk: add non HAVE_CLK routines) added shims for
> the clk code but HAVE_CLK isn't enough. It's possible to have the
> clk support but not enable it. We end up with full prototypes for code
> that is never built - causing module linking to fail later.
> 
> This patch changes the guard to use COMMON_CLK, which actually guards
> the code.

This is wrong.  COMMON_CLK is an _implementation_ of the CLK API.  It
is not the only implementation in the kernel.  Conditionalizing like
this breaks existing users.

HAVE_CLK is the right thing here - if you define HAVE_CLK then you _are_
providing an implementation of clk_get() et.al.  If you're not, then you
do not define HAVE_CLK.  Simples.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:
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