linux-kernel - Re: [PATCH v2] clkdev: add devm_of_clk

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Date:	Fri, 8 Jul 2016 00:03:00 +0000
From:	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To:	Russell King - ARM Linux <linux@...linux.org.uk>
CC:	Michael Turquette <mturquette@...libre.com>,
	Rob Herring <robh@...nel.org>, Mark Brown <broonie@...nel.org>,
	Linux-Kernel <linux-kernel@...r.kernel.org>,
	Linux-DT <devicetree@...r.kernel.org>,
	Linux-ARM <linux-arm-kernel@...ts.infradead.org>,
	Linux-ALSA <alsa-devel@...a-project.org>,
	<linux-clk@...r.kernel.org>
Subject: Re: [PATCH v2] clkdev: add devm_of_clk_get()


Hi Russell

> > > > +struct clk *devm_of_clk_get(struct device *dev,
> > > > +                           struct device_node *np, int index)
> > > 
> > > Any reason not to use devm_clk_get? Why do we need this helper?
> > 
> > Because of_clk_get() can parse "clocks", "#clock-cells" on DT.
> 
> clk_get() should also work just fine.  clk_get() uses
> __of_clk_get_by_name() internally, which uses "clock-names" to
> locate the index if a connection id is given.  of_clk_get() allows
> lookup of a clock by index only, omitting the name, which means
> you need to coordinate the order of clocks in DT with the order
> that the driver wants... which sounds error prone to me.

Thanks.

But, I have 1 issue on [devm_]clk_get().
It can't select device_node on [devm_]clk_get(), it uses dev->of_node directly.

struct clk *clk_get(struct device *dev, const char *con_id)
{
	...
	if (dev) {
		clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id);
		                           ~~~~~~~~~~~~
		...
	}
}

I would like to select specific device_node.

	sound_soc {
		...
		cpu {
			...
=>			clocks = <&xxx>;
		};

		codec {
			...
=>			clocks = <&xxx>;
		};
	};

But, of_clk_get_by_name() / of_clk_get() doesn't have devm_xxx version