linux-kernel - Re: [PATCH v5 3/4] clk: introduce the common clock framework

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Message-ID: <CAJOA=zOV769hz8Bam7TvdXN5AYep66h8H596nK1ETkNAMJBsvQ@mail.gmail.com>
Date:	Fri, 9 Mar 2012 10:18:58 -0800
From:	"Turquette, Mike" <mturquette@...com>
To:	"Turquette, Mike" <mturquette@...com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Andrew Lunn <andrew@...n.ch>, Paul Walmsley <paul@...an.com>,
	linaro-dev@...ts.linaro.org,
	Linus Walleij <linus.walleij@...ricsson.com>,
	patches@...aro.org, Stephen Boyd <sboyd@...eaurora.org>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Magnus Damm <magnus.damm@...il.com>,
	linux-kernel@...r.kernel.org,
	Rob Herring <rob.herring@...xeda.com>,
	Richard Zhao <richard.zhao@...aro.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Deepak Saxena <dsaxena@...aro.org>,
	Saravana Kannan <skannan@...eaurora.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Shawn Guo <shawn.guo@...escale.com>,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Russell King <linux@....linux.org.uk>,
	Jeremy Kerr <jeremy.kerr@...onical.com>,
	Arnd Bergman <arnd.bergmann@...aro.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 3/4] clk: introduce the common clock framework

On Wed, Mar 7, 2012 at 10:27 PM, Andrew Lunn <andrew@...n.ch> wrote:
>> Assuming that some day OMAP code can be refactored to allow for lazy
>> (or at least initcall-based) registration of clocks then perhaps your
>> suggestion can take root.  Which leads me to this question: are there
>> any other platforms out there that require the level of expose to
>> struct clk present in this patchset?  OMAP does, for now, but if that
>> changes then I need to know if others require this as well.
>
> Hi Mike
>
> For kirkwood, i use static clk's for all but my root clock. I cannot
> statically know the rate of the root clock, so i have to determine it
> at boot time using heuristics, PCI ID, etc.
>
> I used statics thinking it would be less code. No idea if it actually
> is, and there is nothing stopping me moving to creating the clocks
> after creating the root clock.
>
> One comment i have about the current static clks. I completely missing
> you need to call __clk_init() on them and so ended up with lots of
> division by zero errors, since they did not have a parent, and so the
> code seemed not be to able to determine the rate.
>
> So
>
> 1) Please add __clk_init() to the documentation in the section about
>   static clocks.

Done.

>
> 2) Should maybe the name change? It seems strange having to call a
>   __X() function. If this is a function which is supposed to be used,
>   drop the __. Maybe clk_static_register()?

That function is used internally by clk_register and is only exposed
by clk-private.h, so I think the naming scheme is sane.  I basically
want to create a sense of worry in anyone using clk-private.h :-)

>
> 3) Maybe, if the parent is missing, clk_get_rate() should return an
>   error?

Non-root, non-fixed-rate, orphan clocks can return an error in this
case.  Will update for V6.  Any idea on best -EERROR?  I'm thinking
ENODEV, but ECHILD and EPIPE are kinda funny in this context.

Regards,
Mike

>
> Andrew
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