linux-kernel - Re: [PATCH v6 1/2] rust: regulator: add a bare minimum regulator abstraction

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Message-Id: <0FD01582-58D1-4DC2-89DB-A4C8771F7750@collabora.com>
Date: Wed, 2 Jul 2025 10:14:04 -0300
From: Daniel Almeida <daniel.almeida@...labora.com>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: Miguel Ojeda <ojeda@...nel.org>,
 Alex Gaynor <alex.gaynor@...il.com>,
 Boqun Feng <boqun.feng@...il.com>,
 Gary Guo <gary@...yguo.net>,
 Björn Roy Baron <bjorn3_gh@...tonmail.com>,
 Benno Lossin <benno.lossin@...ton.me>,
 Andreas Hindborg <a.hindborg@...nel.org>,
 Trevor Gross <tmgross@...ch.edu>,
 Danilo Krummrich <dakr@...nel.org>,
 Boris Brezillon <boris.brezillon@...labora.com>,
 Sebastian Reichel <sebastian.reichel@...labora.com>,
 Liam Girdwood <lgirdwood@...il.com>,
 Mark Brown <broonie@...nel.org>,
 linux-kernel@...r.kernel.org,
 rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v6 1/2] rust: regulator: add a bare minimum regulator
 abstraction


> 
>>>> +impl<T: RegulatorState + 'static> Drop for Regulator<T> {
>>>> +    fn drop(&mut self) {
>>>> +        if core::any::TypeId::of::<T>() == core::any::TypeId::of::<Enabled>() {
>>> 
>>> I would avoid this kind of logic. Instead, you can add an
>>> `disable_on_drop()` method or constant to the trait and check it here.
>>> 
>>> Alice
>>> 
>> 
>> Can you expand on this?
> 
> Along these lines:
> 
> pub trait RegulatorState: 'static {
>    const DISABLE_ON_DROP: bool;
> }
> 
> impl RegulatorState for Enabled {
>    const DISABLE_ON_DROP: bool = true;
> }
> impl RegulatorState for Disabled {
>    const DISABLE_ON_DROP: bool = false;
> }
> impl RegulatorState for Dynamic {
>    const DISABLE_ON_DROP: bool = false;
> }
> 
> impl<T: RegulatorState> Drop for Regulator<T> {
>    fn drop(&mut self) {
>        if T::DISABLE_ON_DROP {
>            unsafe { bindings::regulator_disable(self.inner.as_ptr()) };
>        }
>        unsafe { bindings::regulator_put(self.inner.as_ptr()) };
>    }
> }

Ah, that indeed looks better, thanks.

— Daniel