linux-kernel - Re: [RFC PATCH V3 8/8] cpufreq: Add Rust based cpufreq-dt driver

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Message-ID: <20240711060601.fmnttgqhbh2pitzj@vireshk-i7>
Date: Thu, 11 Jul 2024 11:36:01 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Alice Ryhl <aliceryhl@...gle.com>, Boqun Feng <boqun.feng@...il.com>,
	Danilo Krummrich <dakr@...hat.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Wedson Almeida Filho <wedsonaf@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...sung.com>, linux-pm@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Stephen Boyd <sboyd@...nel.org>, Nishanth Menon <nm@...com>,
	rust-for-linux@...r.kernel.org,
	Manos Pitsidianakis <manos.pitsidianakis@...aro.org>,
	Erik Schilling <erik.schilling@...aro.org>,
	Alex Bennée <alex.bennee@...aro.org>,
	Joakim Bech <joakim.bech@...aro.org>, Rob Herring <robh@...nel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH V3 8/8] cpufreq: Add Rust based cpufreq-dt driver

On 10-07-24, 17:28, Danilo Krummrich wrote:
> No, the platform driver layer will only guarantee that it decreses the reference
> count of the `Arc` by one, that doesn't guarantee a free. If something else
> still holds a reference to the `Arc` it will keep the `Registration` alive,
> unless it's wrapped by `Devres`.

I see. Thanks.

There is one problem that I haven't found a solution to yet. If I make
the following change to the driver:

diff --git a/drivers/cpufreq/rcpufreq_dt.rs b/drivers/cpufreq/rcpufreq_dt.rs
index 315adca2a747..052ea2db095a 100644
--- a/drivers/cpufreq/rcpufreq_dt.rs
+++ b/drivers/cpufreq/rcpufreq_dt.rs
@@ -236,7 +236,7 @@ fn probe(dev: &mut platform::Device, _id_info: Option<&Self::IdInfo>) -> Result<

 module_platform_driver! {
     type: CPUFreqDTDriver,
-    name: "cpufreq_dt",
+    name: "cpufreq-dt",
     author: "Viresh Kumar <viresh.kumar@...aro.org>",
     description: "Generic CPUFreq DT driver",
     license: "GPL v2",

then I get this error:

  CLIPPY     drivers/cpufreq/rcpufreq_dt.o
error: expected one of `:`, `;`, or `=`, found `-`
   --> /mnt/ssd/all/work/repos/kernel/linux/drivers/cpufreq/rcpufreq_dt.rs:237:1
    |
237 | / module_platform_driver! {
238 | |     type: CPUFreqDTDriver,
239 | |     name: "cpufreq-dt",
240 | |     author: "Viresh Kumar <viresh.kumar@...aro.org>",
241 | |     description: "Generic CPUFreq DT driver",
242 | |     license: "GPL v2",
243 | | }
    | |_^ expected one of `:`, `;`, or `=`
    |
    = note: this error originates in the macro
    `$crate::prelude::module` which comes from the expansion of the
    macro `module_platform_driver` (in Nightly builds, run with -Z
    macro-backtrace for more info)


And because of that I had to change the name of the platform device
too in the existing kernel.

-- 
viresh