linux-kernel - Re: [PATCH V2 2/2] rust: Add basic bindings for clk APIs

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Message-ID: <20250306044810.mqbo74nc6ch4dauw@vireshk-i7>
Date: Thu, 6 Mar 2025 10:18:10 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Rob Herring <robh@...nel.org>
Cc: Sebastian Reichel <sebastian.reichel@...labora.com>,
	Danilo Krummrich <dakr@...nel.org>,
	Daniel Almeida <daniel.almeida@...labora.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, 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>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	Russell King <linux@...linux.org.uk>, linux-clk@...r.kernel.org,
	linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org
Subject: Re: [PATCH V2 2/2] rust: Add basic bindings for clk APIs

On 05-03-25, 14:09, Rob Herring wrote:
> Either way, but generally I think 2 functions are preferred over 1
> function and flags.
> 
> The harder part here is in C we just return NULL and all subsequent
> functions (e.g. clk_enable()) just return with no error for a NULL
> struct clk. For rust, I think we'd need a dummy Clk returned and then
> handle comparing the passed in reference to the dummy Clk in the rust
> bindings.

I have implemented it differently in V3:

https://lore.kernel.org/all/023e3061cc164087b9079a9f6cb7e9fbf286794e.1740995194.git.viresh.kumar@linaro.org/

So even for a NULL value returned from clk_get_optional(), Rust users still get
OptionalClk (Deref as Clk) and they keep using it as if a valid Clk is returned
and will keep calling all clk APIs (which will return early for NULL clks).

-- 
viresh