linux-kernel - Re: [PATCH v2 2/7] pwm: Add Rust driver for T-HEAD TH1520 SoC

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Message-ID: <02e480b9-68eb-47e7-97f5-54e49d259f84@samsung.com>
Date: Wed, 11 Jun 2025 23:15:57 +0200
From: Michal Wilczynski <m.wilczynski@...sung.com>
To: Uwe Kleine-König <ukleinek@...nel.org>
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>, Andreas
	Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, Trevor
	Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>, Drew Fustini
	<drew@...7.com>, Guo Ren <guoren@...nel.org>, Fu Wei <wefu@...hat.com>, Rob
	Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor
	Dooley <conor+dt@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>, Marek Szyprowski
	<m.szyprowski@...sung.com>, Benno Lossin <lossin@...nel.org>, Michael
	Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>,
	linux-kernel@...r.kernel.org, linux-pwm@...r.kernel.org,
	rust-for-linux@...r.kernel.org, linux-riscv@...ts.infradead.org,
	devicetree@...r.kernel.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 2/7] pwm: Add Rust driver for T-HEAD TH1520 SoC



On 6/11/25 22:04, Michal Wilczynski wrote:
> 
> 
> On 6/11/25 08:58, Uwe Kleine-König wrote:
>> Hello,
>>
>>
>> What does .unwrap_or(0) do? You need to round up in this mul_div
>> operation.

Yeah and I'm thinking that the helper needs to be updated or new one
added like mul_div_round_up, to do the rounding

> 
> The .unwrap_or(0) is to handle the case where the mul_div helper returns
> None, which can happen if the divisor (rate_hz) is zero. In that case,
> the period  becomes 0. The mul_div helper is introduced in this commit
> [1].
> 
> [1] - https://lore.kernel.org/all/20250609-math-rust-v1-v1-1-285fac00031f@samsung.com/
> 


Best regards,
-- 
Michal Wilczynski <m.wilczynski@...sung.com>