linux-kernel - Re: [PATCH] clk: prevent __of_clk_get_hw_from

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Message-id: <792d2cb8-06bf-7406-b79a-06c16b977bd4@samsung.com>
Date:	Fri, 05 Aug 2016 10:29:39 +0200
From:	Sylwester Nawrocki <s.nawrocki@...sung.com>
To:	Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:	Stephen Boyd <sboyd@...eaurora.org>, linux-clk@...r.kernel.org,
	Michael Turquette <mturquette@...libre.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: prevent __of_clk_get_hw_from_provider() from
 returning NULL

On 08/04/2016 10:57 PM, Stephen Boyd wrote:
> On 07/19, Masahiro Yamada wrote:
>> > The .get(_hw) callback of an OF clock provider can return a NULL
>> > pointer in some cases.
>> > 
>> > For example, of_clk_src_onecell_get() returns NULL for index 1 of a
>> > sparse array of clocks like follows:
>> > 
>> >   clk_num == 3
>> >   idx 0: UART clk
>> >   idx 1: NULL (no clk is allocated)
>> >   idx 2: I2C clk
>> > 
>> > In such cases, clk_get() successfully returns NULL.

I remember running into same issue before, we have addressed
it by initializing the array of clocks with some errno value,
e.g ERR_PTR(-ENOENT), so there is no chance to get NULL from
the array - either a valid clk pointer or an ERR_PTR() value.

--
Thanks,
Sylwester