linux-kernel - Re: [PATCH v8 04/10] reset: eyeq5: add platform driver

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Date: Thu, 29 Feb 2024 15:48:59 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Théo Lebrun <theo.lebrun@...tlin.com>
Cc: Gregory CLEMENT <gregory.clement@...tlin.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh+dt@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
	Linus Walleij <linus.walleij@...aro.org>,
	Rafał Miłecki <rafal@...ecki.pl>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>,
	linux-mips@...r.kernel.org, linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Tawfik Bayouk <tawfik.bayouk@...ileye.com>,
	linux-gpio@...r.kernel.org
Subject: Re: [PATCH v8 04/10] reset: eyeq5: add platform driver

On Thu, Feb 29, 2024 at 01:18:08PM +0100, Théo Lebrun wrote:
> On Thu Feb 29, 2024 at 12:22 PM CET, Andy Shevchenko wrote:
> > On Wed, Feb 28, 2024 at 06:04:47PM +0100, Théo Lebrun wrote:
> > > On Tue Feb 27, 2024 at 6:27 PM CET, Andy Shevchenko wrote:
> > > > On Tue, Feb 27, 2024 at 03:55:25PM +0100, Théo Lebrun wrote:

..

> > > > > +	priv->rcdev.of_node = np;
> > > >
> > > > It's better to use device_set_node().
> > > 
> > > I don't see how device_set_node() can help? It works on struct device
> > > pointers. Here priv->rcdev is a reset_controller_dev struct. There are
> > > no users of device_set_node() in drivers/reset/.
> >
> > No users doesn't mean it's good. The API is relatively "new" and takes
> > care of two things:
> > 1) it uses agnostic interface;
> > 2) it doesn't require any firmware node direct dereference.
> >
> > The 2) is most important here as allows us to refactor (firmware node) code
> > in the future.
> 
> I think I get the point of device_set_node(). I still do not understand
> how it could help me fill the ->of_node field in a reset_controller_dev
> structure?

Exactly why I put the above comment as recommendation. And then I elaborated
that entire reset framework should rather move towards fwnode.

> Should I be using device_set_node() to fill the struct device pointer
> and the reset subsystem, by some magic, will pick this up and use it
> for its own of_node field? I've not seen any magic/code doing that.

At bare minimum it will give beneficial things:
1) less burden in the drivers conversion in case fwnode happens (and I believe
   it's just matter of time) in reset framework;
2) hiding fwnode/of_node implemetation details (which is currently is layering
   violation to some extend (as we have a lot of *of_*() APIs to avoid direct
   access to of_node field in struct device).

The downside is that you will need to include property.h for this only thing.
And I don't see other code that can be converted to fwnode right away here.

-- 
With Best Regards,
Andy Shevchenko