linux-kernel - Re: [PATCH v3 1/3] rust: clk: use the type-state pattern

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Message-ID: <20260119-tall-proficient-quetzal-e5e3ad@houat>
Date: Mon, 19 Jan 2026 15:27:27 +0100
From: Maxime Ripard <mripard@...nel.org>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: Daniel Almeida <daniel.almeida@...labora.com>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Viresh Kumar <viresh.kumar@...aro.org>, 
	Danilo Krummrich <dakr@...nel.org>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Drew Fustini <fustini@...nel.org>, Guo Ren <guoren@...nel.org>, 
	Fu Wei <wefu@...hat.com>, Uwe Kleine-König <ukleinek@...nel.org>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Miguel Ojeda <ojeda@...nel.org>, 
	Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
	Björn Roy Baron <bjorn3_gh@...tonmail.com>, Benno Lossin <lossin@...nel.org>, 
	Andreas Hindborg <a.hindborg@...nel.org>, Trevor Gross <tmgross@...ch.edu>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, linux-riscv@...ts.infradead.org, 
	linux-pwm@...r.kernel.org, linux-clk@...r.kernel.org, rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v3 1/3] rust: clk: use the type-state pattern

On Mon, Jan 19, 2026 at 12:35:21PM +0000, Alice Ryhl wrote:
> > > In fact, I specifically wanted to ensure that this was possible when writing
> > > these patches, as it’s needed by drivers. If you want to, I can cover that in
> > > the examples, no worries.
> > 
> > Yes, that would be great. I do wonder though if it wouldn't make sense
> > to turn it the other way around. It creates a fair share of boilerplate
> > for a number of drivers. Can't we keep Clk the way it is as a
> > lower-level type, and crate a ManagedClk (or whatever name you prefer)
> > that drivers can use, and would be returned by higher-level helpers, if
> > they so choose?
> > 
> > That way, we do have the typestate API for whoever wants to, without
> > creating too much boilerplate for everybody else.
> 
> I think that if you still want an API where you just call enable/disable
> directly on it with no protection against unbalanced calls, then that
> should be the special API. Probably called RawClk and functions marked
> unsafe. Unbalanced calls seem really dangerous and use should not be
> encouraged.

Sure, that makes sense to me.

> The current type-state based API is the least-boilerplate option for
> drivers that exist today.

I wasn't saying that we should add boilerplate to the typestate API
either. I was saying that the non-typestated API was common enough that
we probably didn't want boilerplate for it either if possible.

Maxime

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