linux-kernel - Re: [PATCH 1/4] clk: Add a generic clock infrastructure

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Date:	Fri, 20 May 2011 13:59:36 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Jeremy Kerr <jeremy.kerr@...onical.com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-sh@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/4] clk: Add a generic clock infrastructure

Hi Jeremy,

Nice to see progress in this area :)

On Fri, May 20, 2011 at 03:27:49PM +0800, Jeremy Kerr wrote:
> +
> +struct clk *clk_register(struct clk_hw_ops *ops, struct clk_hw *hw,
> +		const char *name)
> +{
> +	struct clk *clk;
> +
> +	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
> +	if (!clk)
> +		return NULL;
> +
> +	clk->name = name;
> +	clk->ops = ops;
> +	clk->hw = hw;
> +	hw->clk = clk;

is it worth to add a CLK_REGISTERED flag here? Up to now clocks do not
have to be registered at all and the registering might be forgotten for
some clocks. I suppose funny things can happen when we operate on
unregistered clocks.

> +
> +	/* Query the hardware for parent and initial rate */
> +
> +	if (clk->ops->get_parent)
> +		/* We don't to lock against prepare/enable here, as
> +		 * the clock is not yet accessible from anywhere */
> +		clk->parent = clk->ops->get_parent(clk->hw);
> +
> +	if (clk->ops->recalc_rate)
> +		clk->rate = clk->ops->recalc_rate(clk->hw);

This implicitely requires that we never register a clock before its
parent is registered. This makes perfect sense but I think we should
catch it here when the user tries to register a clock with a not yet
registered parent.

> +
> +
> +	return clk;
> +}
> +EXPORT_SYMBOL_GPL(clk_register);

BTW we planned to let the linker do the job of registering static
clocks, but this is only convenience and can be added later.


Sascha

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