linux-kernel - Re: [PATCH 2/3] clk: let of_clk_get_parent

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Date:	Mon, 30 Nov 2015 17:34:24 +0900
From:	Masahiro Yamada <yamada.masahiro@...ionext.com>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	linux-clk@...r.kernel.org,
	Michael Turquette <mturquette@...libre.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ben Dooks <ben.dooks@...ethink.co.uk>
Subject: Re: [PATCH 2/3] clk: let of_clk_get_parent_name() fail for invalid clock-indices

Hi Stephen,



>>
>> Of course we can, although we have to mention "clock-indices" twice.
>>
>> A good thing for of_get_property() is that we can get both the value
>> and the length
>> at the same time.
>>
>
> Ok. Well if we don't want to count them again, perhaps a goto
> jump over an unconditional return NULL would be better?
>
>         of_property_for_each_u32(clkspec.np, "clock-indices", prop, vp, pv) {
>                 if (index == pv) {
>                         index = count;
>                         goto found;
>                 }
>                 count++;
>         }
>
>         return NULL;
> found:
>
> Or since the macro for of_property_for_each_u32() tests the vp
> poitner for NULL, we can check that pointer too...
>
>         of_property_for_each_u32(clkspec.np, "clock-indices", prop, vp, pv) {
>                 if (index == pv) {
>                         index = count;
>                         break;
>                 }
>                 count++;
>         }
>
>         /* We didn't find anything */
>         if (!vp)
>                 return NULL;
>
> I guess I prefer the latter approach here.
>

No.

Neither of your two suggestions works because they are false positive.

With your way, if "clock-indices" does not exist, of_clk_get_parent_name()
would return NULL;  in this case it should just parse "clock-output-names",
assuming that the clock names are simply indexed from zero.


-- 
Best Regards
Masahiro Yamada
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