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Date: Thu, 25 Apr 2024 15:51:29 +0000
To: Viresh Kumar <viresh.kumar@linaro.org>
From: Benno Lossin <benno.lossin@proton.me>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>, Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>, Miguel Ojeda <ojeda@kernel.org>, Alex Gaynor <alex.gaynor@gmail.com>, Wedson Almeida Filho <wedsonaf@gmail.com>, Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>, =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>, Andreas Hindborg <a.hindborg@samsung.com>, Alice Ryhl <aliceryhl@google.com>, linux-pm@vger.kernel.org, Vincent Guittot <vincent.guittot@linaro.org>, Stephen Boyd <sboyd@kernel.org>, Nishanth Menon <nm@ti.com>, rust-for-linux@vger.kernel.org, Manos Pitsidianakis <manos.pitsidianakis@linaro.org>, Erik Schilling <erik.schilling@linaro.org>, =?utf-8?Q?Alex_Benn=C3=A9e?= <alex.bennee@linaro.org>, Joakim Bech <joakim.bech@linaro.org>, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/3] rust: Add bindings for OPP framework
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On 22.04.24 12:24, Viresh Kumar wrote:
> Thanks for the review Benno. I was waiting for more review comments to
> come in and hence didn't reply earlier with an update.
>=20
> On 07-04-24, 09:54, Benno Lossin wrote:
>> On 05.04.24 13:09, Viresh Kumar wrote:
>>> +    clk_names: Option<Pin<Vec<CString>>>,
>>
>> Why are you using `Pin<Vec<_>>`? The vector may reallocate the backing
>> storage at any point in time.
>=20
>>> +    /// Sets the configuration with the OPP core.
>>> +    pub fn set(&mut self, dev: &Device) -> Result<()> {
>>> +        // Already configured.
>>> +        if self.token.is_some() {
>>
>> Why does the config hold onto this token? Would it make sense to consume
>> the config and return a `Handle` or `Token` abstraction? Then you don't
>> need to check if the config has been "used" before.
>=20
>>> +#[repr(transparent)]
>>> +pub struct OPP(*mut bindings::dev_pm_opp);
>>
>> I think you should use the `ARef` pattern instead:
>>
>>       #[repr(transparent)]
>>       pub struct OPP(Opaque<bindings::dev_pm_opp>);
>>
>>       unsafe impl AlwaysRefCounted for OPP {
>>           // ...
>>       }
>>
>> Then you can use `ARef<OPP>` everywhere you use `OPP` currently.
>=20
> All these comments look good to me. Updated the code with them (not
> reposting them for now)

I currently do not have a lot of time, so I will re-review it when you
post a new version.

> -------------------------8<-------------------------
>=20
>  rust/bindings/bindings_helper.h |   1 +
>  rust/kernel/lib.rs              |   2 +
>  rust/kernel/opp.rs              | 888 ++++++++++++++++++++++++++++++++

One other nice thing that you could do would be to split this patch into
multiple smaller ones. That makes understanding the pieces a lot easier.

--=20
Cheers,
Benno