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

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Message-ID: <CAK7LNATzraLEavLGHR0c1-0J1-CzvCsfgW1URitAFOnej7+-Ug@mail.gmail.com>
Date:	Tue, 24 Nov 2015 13:25:08 +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>
Subject: Re: [PATCH 3/3] clk: split of_clk_get_parent_name() into two functions

Hi Stephen,


2015-11-22 14:44 GMT+09:00 Masahiro Yamada <yamada.masahiro@...ionext.com>:
> Hi Stephen,
>
>
> 2015-11-21 9:37 GMT+09:00 Stephen Boyd <sboyd@...eaurora.org>:
>> On 11/20, Masahiro Yamada wrote:
>>> Currently, there is no function to get the clock name of the given
>>> node.  Create a new helper function, of_clk_get_name().  This is
>>> useful to get the clock name where "clock-indices" property is used.
>>>
>>>   of_clk_get_name(): get the clock name in the given node
>>>   of_clk_get_parent_name(): get the name of the parent clock
>>>
>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
>>> ---
>>>
>>> I want to use of_clk_get_name() for my clk drivers for my SoCs,
>>> which I will submit later.
>>>
>>> I found this helper function is useful.
>>
>> I don't see how this is useful. Is the new driver so generic it
>> doesn't know what clocks it's outputting? We've been trying to
>> move people away from using clock-output-names, so most likely
>> this sort of information should be conveyed from DT via the
>> compatible string and a table in the driver that matches up the
>> compatible string with the list of clock names.
>
>
> What I implemented in my driver was:
>
> [1] Use the clock names built in the driver, if "clock-output-names"
>     is missing in the DT.
>
> [2] If "clock-output-names" is specified, the driver overrides
>     the clock names, respecting the "clock-output-names".
>
>
> The following is a snippet from my driver code.
>
>
>     /*
>      * update the clock name with the one provided by
>      * clock-output-names property, if exists
>      */
>     new_name = of_clk_get_name(np, index);
>     if (new_name)
>             init_data[i].name = new_name;
>     else
>             pr_info("DT does not specify output name for %s[%d]\n",
>                     np->name, index);
>
>
> I read the Documentation/devicetree/bindings/clock-bindings.txt
> before I stared my driver development.
>
> I did not know we are deprecating the "clock-output-names".
> (Should it be mentioned in the clock-bindings.txt?)




Please let me clarify the driver implementation guideline.

[1] Do not add "clock-output-names" in new device trees.
[2] New clock drivers should not rely on "clock-output-names" at all.


Is this correct?




-- 
Best Regards
Masahiro Yamada
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