linux-kernel - Re: [PATCH 2/3] clk: samsung: Add clock driver for s5pc100

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Date:	Fri, 27 Sep 2013 18:37:56 +0530
From:	Yadwinder Singh Brar <yadi.brar01@...il.com>
To:	Tomasz Figa <t.figa@...sung.com>
Cc:	Mateusz Krawczuk <m.krawczuk@...tner.samsung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Mark Rutland <mark.rutland@....com>,
	devicetree <devicetree@...r.kernel.org>,
	Yadwinder Singh <yadi.brar@...sung.com>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	Mike Turquette <mturquette@...aro.org>,
	Rob Landley <rob@...dley.net>, Pawel Moll <pawel.moll@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	ijc+devicetree@...lion.org.uk,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Rob Herring <rob.herring@...xeda.com>, ben-linux@...ff.org,
	s.nawrocki@...sung.com,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/3] clk: samsung: Add clock driver for s5pc100

Hi Tomasz,

On Thu, Sep 26, 2013 at 7:30 PM, Tomasz Figa <t.figa@...sung.com> wrote:
> Hi Yadwinder,
>
> I haven't reviewed this series yet, but let me clarify some things from
> your comments.
>
> On Thursday 26 of September 2013 17:38:58 Yadwinder Singh Brar wrote:
>> > +
>> > +/* Helper macros to define clock arrays. */
>> > +#define FIXED_RATE_CLOCKS(name)        \
>> > +               static struct samsung_fixed_rate_clock name[]
>> > +#define MUX_CLOCKS(name)       \
>> > +               static struct samsung_mux_clock name[]
>> > +#define DIV_CLOCKS(name)       \
>> > +               static struct samsung_div_clock name[]
>> > +#define GATE_CLOCKS(name)      \
>> > +               static struct samsung_gate_clock name[]
>> > +
>>
>> These macros seems little bit odd in our common practice,
>> perhaps these are making code harder to read below.
>>
>
> They allow array declaration to fit into single line. I agree that it is
> not particularly easy to read at first sight, but shouldn't really be
> much of nuisance.

Defining a macro just to use once/twice, especially hiding the
definition of some array, doesn't looks justified.

>In addition, most of this driver is based on macros
> like this, e.g. GATE(), MUX(), PNAME(), etc.
>
>> > +PNAME(mout_i2s_2_p) = {
>> > +       "fout_epll",
>> > +       "i2scdclk0",
>> > +       "dout_audio0",
>> > +       "none"
>> > +};
>> > +
>>
>> Using one line per parent isn't increasing length of file unnecessarily?
>
> I believe this improves readability. Do we really care about size of
> source code that much, over readability?
>

yes, its looks little bit clean but in this case I felt, its making
the traversability in file difficult due to length of file.

>> > +       ALIAS(SCLK_AUDIO0, "soc-audio.0", "sclk_audio"),
>> > +       ALIAS(SCLK_AUDIO1, "soc-audio.1", "sclk_audio"),
>> > +       ALIAS(SCLK_AUDIO2, "soc-audio.2", "sclk_audio"),
>> > +       ALIAS(KEYIF, NULL, "keypad"),
>> > +
>> > +       ALIAS(MFC, "s5p-mfc", "sclk_mfc"),
>> > +       ALIAS(G2D, "s5p-g2d", "fimg2d"),
>> > +
>> > +};
>> > +
>>
>> Any reason/hidden advantage for using a separate of ALIAS,
>> instead of using MUX_A/GATE_A ?
>
> Yes, not even hidden. Alias is not a property of clock. One clock can
> have multiple aliases, e.g. the same clock being input to multiple
> devices.
>

Yes, its required if same clk has different alias for different devices,
but while using same alias for different(all, in this case) devices,
doesn't seems advantageous.

Regards,
Yadwinder
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