linux-kernel - Re: [PATCH 7/8] reset: amlogic: add auxiliary reset driver support

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Message-ID: <1jzfqho5pp.fsf@starbuckisacylon.baylibre.com>
Date: Thu, 18 Jul 2024 09:05:52 +0200
From: Jerome Brunet <jbrunet@...libre.com>
To: Stephen Boyd <sboyd@...nel.org>
Cc: Neil Armstrong <neil.armstrong@...aro.org>,  Philipp Zabel
 <p.zabel@...gutronix.de>,  Jan Dakinevich
 <jan.dakinevich@...utedevices.com>,  linux-kernel@...r.kernel.org,
  linux-amlogic@...ts.infradead.org,  linux-clk@...r.kernel.org
Subject: Re: [PATCH 7/8] reset: amlogic: add auxiliary reset driver support

On Mon 15 Jul 2024 at 12:30, Stephen Boyd <sboyd@...nel.org> wrote:

>> >> +int devm_meson_rst_aux_register(struct device *dev,
>> >> +                               struct regmap *map,
>> >> +                               const char *adev_name);
>> >> +#else
>> >> +static inline int devm_meson_rst_aux_register(struct device *dev,
>> >> +                                             struct regmap *map,
>> >> +                                             const char *adev_name)
>> >> +{
>> >> +       return -EOPNOTSUPP;
>> >
>> > Shouldn't this be 'return 0' so that the clk driver doesn't have to care
>> > about the config?
>> 
>> I don't think the system (in general) would be able function without the reset
>> driver, so the question is rather phylosophical.
>> 
>> Let's say it could, if this returns 0, consumers of the reset controller
>> will defer indefinitely ... which is always a bit more difficult to sort
>> out.
>> 
>> If it returns an error, the problem is pretty obvious, helping people
>> solve it quickly.
>> 
>> Also the actual device we trying to register provides clocks and reset.
>> It is not like the reset is an optional part we don't care about.
>> 
>> On this instance it starts from clock, but it could have been the other
>> way around. Both are equally important.
>> 
>> I'd prefer if it returns an error when the registration can't even start.
>> 
>
> Ok. Fair enough.

Actually, thinking about it more I changed my mind and I tend to agree
on 'return 0' which I'll use in the next version.

The initial request was to de-couple clk and reset. I was planning on
having clk 'imply' reset to have a weak dependency. That does not make
sense if an error is returned above. I would have to use 'depends on' and
don't like it in that case, sooo weak dependency it is.

It remains fairly easy to change later on if necessary

-- 
Jerome