linux-kernel - Re: [PATCH v14 17/18] media: i2c: ds90ub953: Restructure clkout management

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Date:   Mon, 19 Jun 2023 14:11:09 +0300
From:   Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To:     Andy Shevchenko <andriy.shevchenko@...el.com>
Cc:     linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
        Luca Ceresoli <luca.ceresoli@...tlin.com>,
        Matti Vaittinen <Matti.Vaittinen@...rohmeurope.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Wolfram Sang <wsa@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Peter Rosin <peda@...ntia.se>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Michael Tretter <m.tretter@...gutronix.de>,
        Hans Verkuil <hverkuil@...all.nl>,
        Mike Pagano <mpagano@...too.org>,
        Krzysztof Hałasa <khalasa@...p.pl>,
        Marek Vasut <marex@...x.de>,
        Satish Nagireddy <satish.nagireddy@...cruise.com>
Subject: Re: [PATCH v14 17/18] media: i2c: ds90ub953: Restructure clkout
 management

On 19/06/2023 13:44, Andy Shevchenko wrote:
> On Mon, Jun 19, 2023 at 01:14:34PM +0300, Tomi Valkeinen wrote:
>> On 16/06/2023 17:37, Andy Shevchenko wrote:
>>> On Fri, Jun 16, 2023 at 04:59:21PM +0300, Tomi Valkeinen wrote:
>>>> Separate clkout calculations and register writes into two functions:
>>>> ub953_calc_clkout_params and ub953_write_clkout_regs, and add a struct
>>>> ub953_clkout_data that is used to store the clkout parameters.
> 
> ...
> 
>>>> +struct ub953_clkout_data {
>>>> +	u32 hs_div;
>>>> +	u32 m;
>>>> +	u32 n;
>>>
>>> Please, use struxt u32_fract instead of m/n.
>>
>> I'm not sure how that helps. The documentation talks about m and n. Using
>> different terms will make it more difficult to compare the code and the
>> docs.
> 
> You can always add a comment.
> 
> (For example in drivers/clk/clk-fractional-divider.c our documentation also
>   says about m/n, but most of the people understands that this is about
>   fractional divider and actually with properly spelled parameters it will
>   help others who are not experts in the CLK hardware.)

Yes, I would agree with you if this was a generic piece of code, but I 
don't see the reasoning as valid as this is specific to a piece of 
hardware. Here, I think, matching the code to the HW documentation is 
more important than possibly making the code more understandable to 
people who are not familiar with the HW.

Especially as for non-English people seeing "numerator" and 
"denominator" might require a check to figure out which one is which, 
whereas m and n are (I would guess) a bit more universal (or maybe it's 
just me).

  Tomi