linux-kernel - Re: [PATCH 2/2] clkdev: Implement managed clk

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Date:	Mon, 02 Apr 2012 10:16:03 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Mike Turquette <mturquette@...com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/2] clkdev: Implement managed clk_get()

On 04/02/12 10:08, Russell King - ARM Linux wrote:
> On Mon, Apr 02, 2012 at 10:04:03AM -0700, Stephen Boyd wrote:
>> On 04/02/12 09:52, Russell King - ARM Linux wrote:
>>> On Mon, Apr 02, 2012 at 09:48:31AM -0700, Stephen Boyd wrote:
>>>> I hope we get a better clk_get() implementation with the unified struct
>>>> clk. Don't get me wrong, clkdev is a great improvement over open coding
>>>> clock framework stuff in each platform. But clkdev is really just
>>>> another platform specific implementation
>>> Utter crap.  It is not platform specific.
>> It has compile-time platform hooks so it isn't entirely generic.
> Compile time hooks which are necessary to ensure safety of the provided
> struct clk.  You can't implement a clk_get() which doesn't have either
> knowledge of the struct clk or some kind of hook into platform specific
> code.  That's a hard and unarguable fact.
>
>>>> that most platforms decide to
>>>> use. Each platform has to select the option and it breaks if two
>>>> platforms implement __clk_get()/__clk_put() in conflicting ways.
>>> They should go away with the common clock stuff: they are there to deal
>>> with the implementation specific parts of struct clk, and as the common
>>> clock stuff sorts that out, these should be provided by the common clk.
>> Agreed. They should all be deleted and only one should exist.
> Utter crap.  Deleting them makes the non-common clock implementations
> unsafe.  If a struct clk is provided by a module (and we do have some
> which are) then the module reference count has to be held.  That's
> what these hooks do.
>
> When these platforms get converted over to the common clock, and the
> issues surrounding dynamically registered and removed clocks are sane,
> these hooks have to be used by the common clock to deal with the
> refcounting so that common code knows when the structures can be freed.

I'm saying that when every platform is using the common clock code we
would only have one __clk_get() implementation and we should be able to
delete clkdev.h entirely.

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

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