linux-kernel - Re: [PATCH 2/2] clk: Move init fields from clk to clk

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Date:	Tue, 20 Mar 2012 13:14:51 -0700
From:	Saravana Kannan <skannan@...eaurora.org>
To:	Sascha Hauer <s.hauer@...gutronix.de>
CC:	Shawn Guo <shawn.guo@...aro.org>,
	Mike Turquette <mturquette@...aro.org>,
	Arnd Bergman <arnd.bergmann@...aro.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
	Rob Herring <rob.herring@...xeda.com>,
	Russell King <linux@....linux.org.uk>,
	Jeremy Kerr <jeremy.kerr@...onical.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Paul Walmsley <paul@...an.com>,
	Shawn Guo <shawn.guo@...escale.com>,
	Jamie Iles <jamie@...ieiles.com>,
	Richard Zhao <richard.zhao@...aro.org>,
	Magnus Damm <magnus.damm@...il.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Deepak Saxena <dsaxena@...aro.org>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: Re: [PATCH 2/2] clk: Move init fields from clk to clk_hw

On 03/20/2012 11:14 AM, Sascha Hauer wrote:
> On Tue, Mar 20, 2012 at 03:17:10AM -0700, Saravana Kannan wrote:
>>
>> On Tue, March 20, 2012 2:40 am, Sascha Hauer wrote:
>>> On Tue, Mar 20, 2012 at 12:54:55AM -0700, Saravana Kannan wrote:
>>>>
>>> I am using these functions and don't need a static array, I just call
>>> the functions with the desired parameters.
>>
>> Sure, then let's leave it in. Curious, where do you get the desired
>> parameters from? Is it static date in code or is it from DT? You somehow
>> probe it?
>
> It's not from DT. See this thread:
>
> http://www.spinics.net/lists/arm-kernel/msg165839.html

Ah, I see. That's a lot of functions calls. I think it would be much 
more efficient if you just have an array and loop over it. With my 
patch, you can just call a single register function for all these clocks.

>>
>>> Overall the clock framework was written in a way that we have to expose
>>> as little information about the internally used structs as necessary. It
>>> seems your patches are pulling in the opposite direction now.
>>
>> I'm not exposing anything that you don't already pass from the platform
>> driver. Also, you realize that this is very similar to what you suggested
>> with clk_initializer right? If there is a strong push, we can make a copy
>> of these inside the struct clk, but for these few init fields I don't see
>> a point (see earlier email).
>
> The difference is that a struct clk_initializer is only used to
> initialize a clock and not actively used by the clock framework. But as
> you already mentioned using a copy inside the clock framework has the
> same effect.

My opinion on this is to follow a wait and watch approach on the "flags" 
field. I really can't think of a safe way anyone can misuse it. If 
people start doing that, we can just do the copy and let them deal with 
their broken code. Until that happens, I don't want to waste time/space 
by copying it. The rest of the fields aren't actively used by the common 
clock code after init.

Thanks,
Saravana

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