linux-kernel - RE: [PATCH] clk: Add (devm_)clk_get

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Date:   Tue, 20 Nov 2018 10:53:33 +0000
From:   Phil Edworthy <phil.edworthy@...esas.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Russell King <linux@...linux.org.uk>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Huacai Chen <chenhc@...ote.com>, Guan Xuetao <gxt@....edu.cn>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        "linux-m68k@...ts.linux-m68k.org" <linux-m68k@...ts.linux-m68k.org>,
        "linux-mips@...ux-mips.org" <linux-mips@...ux-mips.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH] clk: Add (devm_)clk_get_optional() functions

Hi Andy,

On 20 November 2018 10:39 Andy Shevchenko wrote:
> On Mon, Nov 19, 2018 at 02:12:59PM +0000, Phil Edworthy wrote:
> > This adds clk_get_optional() and devm_clk_get_optional() functions to
> > get optional clocks.
> > They behave the same as (devm_)clk_get except where there is no clock
> > producer. In this case, instead of returning -ENOENT, the function
> > returns NULL. This makes error checking simpler and allows
> > clk_prepare_enable, etc to be called on the returned reference without
> > additional checks.
> 
> >  - Instead of messing with the core functions, simply wrap them for the
> >    _optional() versions. By putting clk_get_optional() inline in the header
> >    file, we can get rid of the arch specific patches as well.
> 
> Fine if it would have no surprises with error handling.
There shouldn't be any surprises. My earlier attempts at implementing this
were hampered by the fact that of_clk_get_by_name() can return -EINVAL
in some circumstances. By directly wrapping the (devm_)clk_get() functions
that problem goes away.

> > +	if (ERR_PTR(-ENOENT))
Huh? That wasn't the code I sent...

> > +		return NULL;
> > +	else
> > +		return clk;
> 
> return clk == ERR_PTR(-ENOENT) ? NULL : clk;
> 
> ?
> 
> > +	if (clk == ERR_PTR(-ENOENT))
> > +		return NULL;
> > +	else
> > +		return clk;
> 
> Ditto.
Sure, will fix both.

Thanks
Phil