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From:   Phil Edworthy <phil.edworthy@renesas.com>
To:     =?iso-8859-1?Q?Uwe_Kleine-K=F6nig?= 
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        <linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH v6 1/6] clk: Add of_clk_get_by_name_optional() function
Thread-Topic: [PATCH v6 1/6] clk: Add of_clk_get_by_name_optional() function
Thread-Index: AQHUfb0RmyNdBSsmakSgPhksP0TsX6VSj8kAgAACxACABFCrgA==
Date:   Mon, 19 Nov 2018 10:41:42 +0000
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Hi Uwe,

On 16 November 2018 16:11 Uwe Kleine-K=F6nig wrote:
> On Fri, Nov 16, 2018 at 05:01:28PM +0100, Uwe Kleine-K=F6nig wrote:
> > Other than that I think the patch is fine
>=20
> Thinking again, I wonder why not just do:
>=20
> static inline struct clk *clk_get_optional(struct device *dev, const char=
 *id) {
> 	struct clk *c =3D clk_get(dev, id);
>=20
> 	if (c =3D=3D ERR_PTR(-ENOENT))
> 		return NULL;
> 	else
> 		return c;
> }

Unfortunately, underneath this __of_clk_get_by_name() returns -EINVAL
when looking for a named clock, and the "clock-names" OF property can't
be found or the name is not in that prop. This is because the index
returned by of_property_match_string() will be an error code and is then
currently always passed to __of_clk_get().

If, as you said, I split the patches into one that fixes the error code, an=
d then
adds clk_get_optional() like above, it will make more sense.

btw, do we need to add of_clk_get_by_name_optional()? I only added it as a
counterpart to of_clk_get_by_name(), but it may not be needed.

Thanks
Phil