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

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Message-ID: <20120320094031.GI3852@pengutronix.de>
Date:	Tue, 20 Mar 2012 10:40:31 +0100
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Saravana Kannan <skannan@...eaurora.org>
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 Tue, Mar 20, 2012 at 12:54:55AM -0700, Saravana Kannan wrote:
> 
> On Tue, March 20, 2012 12:20 am, Shawn Guo wrote:
> > On Mon, Mar 19, 2012 at 08:38:26PM -0700, Saravana Kannan wrote:
> >> This has a couple of advantages:
> >> * Completely hides struct clk from many clock platform drivers and
> >> static
> >>   clock initialization code.
> >> * Simplifies the generic clk_register() function and allows adding
> >> optional
> >>   fields in the future without modifying the function signature.
> >> * Allows for simpler static initialization of clocks on all platforms by
> >>   removing the need for forward delcarations.
> >> * Halves the number of symbols added for each static clock
> >> initialization.
> >>
> >> Signed-off-by: Saravana Kannan <skannan@...eaurora.org>
> >
> > I agree this is a reasonable move.  But while you simplify the interface
> > of clk_register(), why not making a further step to simplify the
> > following interfaces simple too?
> >
> > struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
> >                 const char *parent_name, unsigned long flags,
> >                 unsigned long fixed_rate);
> > struct clk *clk_register_gate(struct device *dev, const char *name,
> >                 const char *parent_name, unsigned long flags,
> >                 void __iomem *reg, u8 bit_idx,
> >                 u8 clk_gate_flags, spinlock_t *lock);
> > struct clk *clk_register_divider(struct device *dev, const char *name,
> >                 const char *parent_name, unsigned long flags,
> >                 void __iomem *reg, u8 shift, u8 width,
> >                 u8 clk_divider_flags, spinlock_t *lock);
> > struct clk *clk_register_mux(struct device *dev, const char *name,
> >                 char **parent_names, u8 num_parents, unsigned long flags,
> >                 void __iomem *reg, u8 shift, u8 width,
> >                 u8 clk_mux_flags, spinlock_t *lock);
> 
> If you simplify those functions further. They would just become
> clk_register(). I'm not sure I see a value in them in at that point or
> even in their current form. But if others see (I'm guessing since they
> acked or didn't nack it), I'm not going to ask to remove them. If everyone
> agrees that we should just remove them, I would be glad to.
> 
> It's arguable that these functions for the common hardware types saves the
> need to deal with the kalloc in every platform driver. But it's not clear
> to me where they would get these parameters in the first place. Most
> likely form some sort of static array. At which point, it might as well be
> a static array of pointers to clk_gated.hw, clk_fixed_rate.hw, etc instead
> of a platform specific  struct to hold these initializers.

I am using these functions and don't need a static array, I just call
the functions with the desired parameters.

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.

Sascha


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