From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout1.w1.samsung.com (mailout1.w1.samsung.com [210.118.77.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3FF0B1AF0CE for ; Wed, 11 Jun 2025 15:14:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=210.118.77.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749654887; cv=none; b=oA5cUZfPCdUDi6NYY1PzqlTEdb7dmVOeKE3SqhRGPdUPbHQBP3zC74JR5aG2HeoBaLbHZ7j7Z6fghUlZWLBhVL0yxqFj+b5g4t9iT4QTqHuq4TS9/GPnNP7X84BSBCjJr8UpwlHtEN3Q5TM69TLWpWZffJvBlztknrt6L7N4lEI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749654887; c=relaxed/simple; bh=pb1NQueabVI9wQkdaC+YDQL17yZ/J3cirFxX0Ib+CQA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:From:In-Reply-To: Content-Type:References; b=MySujDPwEPiANDg98DP6u55cS63qUdpVnC9xAcG02hxh8yvrdWBMfNPJmOBPUDirB9FqQPGUevgo0CEPLB6AYohV7aMJ4+zglN6wOen1vVWuc8HPzarTeFnwcThouco5FbvIYqD3LtBDfK6ApnYb7oup388yK6WUc1MdC+PFG6Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=ihUI4pic; arc=none smtp.client-ip=210.118.77.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="ihUI4pic" Received: from eucas1p1.samsung.com (unknown [182.198.249.206]) by mailout1.w1.samsung.com (KnoxPortal) with ESMTP id 20250611151442euoutp016be74b48138e134daf545a87272fdcb9~IBdiAHKDI3089430894euoutp01V for ; Wed, 11 Jun 2025 15:14:42 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout1.w1.samsung.com 20250611151442euoutp016be74b48138e134daf545a87272fdcb9~IBdiAHKDI3089430894euoutp01V DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1749654882; bh=/aG3yXc2EucpbW7sa9J+WzUETPZ1G5/7AvZ60LGbpt8=; h=Date:Subject:To:Cc:From:In-Reply-To:References:From; b=ihUI4picgtqUec1YrsKY2X8y+lZtQi5PEzaMdY1POhzjEGEKAYKdwrIPJowunk9ho McMbITHYYQQRjiqckByAn6RcHEdimhnM9Ieyp+MhmKyNYPlmxMJ9cYHkMutsHLsxM/ jYGC2BBusGkTjcJqayLlYd3mMorqFK1VDaKlb0y8= Received: from eusmtip2.samsung.com (unknown [203.254.199.222]) by eucas1p1.samsung.com (KnoxPortal) with ESMTPA id 20250611151441eucas1p1c5b30da3e0bd7484b27c9ad78a91f678~IBdhUjG441932119321eucas1p1c; Wed, 11 Jun 2025 15:14:41 +0000 (GMT) Received: from [192.168.1.44] (unknown [106.210.136.40]) by eusmtip2.samsung.com (KnoxPortal) with ESMTPA id 20250611151440eusmtip2d72d1b30d77ba1ed35d675241db8b411~IBdgIHHGO2985829858eusmtip2g; Wed, 11 Jun 2025 15:14:40 +0000 (GMT) Message-ID: <6ca6016e-3b17-48a0-ad8d-bb05317aa100@samsung.com> Date: Wed, 11 Jun 2025 17:14:40 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/7] Rust Abstractions for PWM subsystem with TH1520 PWM driver To: Drew Fustini Cc: =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Guo Ren , Fu Wei , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Marek Szyprowski , Benno Lossin , Michael Turquette , Stephen Boyd , linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org Content-Language: en-US From: Michal Wilczynski In-Reply-To: Content-Transfer-Encoding: 7bit X-CMS-MailID: 20250611151441eucas1p1c5b30da3e0bd7484b27c9ad78a91f678 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20250610125330eucas1p2a573627ca8f124fe11e725c2d75bdcc9 X-EPHeader: CA X-CMS-RootMailID: 20250610125330eucas1p2a573627ca8f124fe11e725c2d75bdcc9 References: <20250610-rust-next-pwm-working-fan-for-sending-v2-0-753e2955f110@samsung.com> On 6/10/25 23:10, Drew Fustini wrote: > On Tue, Jun 10, 2025 at 02:52:48PM +0200, Michal Wilczynski wrote: >> This patch series introduces Rust support for the T-HEAD TH1520 PWM >> controller and demonstrates its use for fan control on the Sipeed Lichee >> Pi 4A board. >> >> The primary goal of this patch series is to introduce a basic set of >> Rust abstractions for the Linux PWM subsystem. As a first user and >> practical demonstration of these abstractions, the series also provides >> a functional PWM driver for the T-HEAD TH1520 SoC. This allows control >> of its PWM channels and ultimately enables temperature controlled fan >> support for the Lichee Pi 4A board. This work aims to explore the use of >> Rust for PWM drivers and lay a foundation for potential future >> Rust based PWM drivers. >> >> The core of this series is a new rust/kernel/pwm.rs module that provides >> abstractions for writing PWM chip provider drivers in Rust. This has >> been significantly reworked from v1 based on extensive feedback. The key >> features of the new abstraction layer include: >> >> - Ownership and Lifetime Management: The pwm::Chip wrapper is managed >> by ARef, correctly tying its lifetime to its embedded struct device >> reference counter. Chip registration is handled by a pwm::Registration >> RAII guard, which guarantees that pwmchip_add is always paired with >> pwmchip_remove, preventing resource leaks. >> >> - Modern and Safe API: The PwmOps trait is now based on the modern >> waveform API (round_waveform_tohw, write_waveform, etc.) as recommended >> by the subsystem maintainer. It is generic over a driver's >> hardware specific data structure, moving all unsafe serialization logic >> into the abstraction layer and allowing drivers to be written in 100% >> safe Rust. >> >> - Ergonomics: The API provides safe, idiomatic wrappers for other PWM >> types (State, Args, Device, etc.) and uses standard kernel error >> handling patterns. >> >> The series is structured as follows: >> - Rust PWM Abstractions: The new safe abstraction layer. >> - TH1520 PWM Driver: A new Rust driver for the TH1520 SoC, built on >> top of the new abstractions. >> - Clock Fix: A necessary fix to the TH1520 clock driver to ensure bus >> clocks remain enabled. >> - Device Tree Bindings & Nodes: The remaining patches add the necessary >> DT bindings and nodes for the TH1520 PWM controller, a thermal >> sensor, and the PWM fan configuration for the Lichee Pi 4A board. >> >> Testing: >> Tested on the TH1520 SoC. The fan works correctly. The duty/period >> calculaties are correct. Fan starts slow when the chip is not hot and >> gradually increases the speed when PVT reports higher temperatures. >> >> The patches are based on mainline, with some dependencies which are not >> merged yet - platform Io support [1] and math wrapper [2]. >> >> Reference repository with all the patches together can be found on >> github [3]. > > I'm trying to build your rust-next-pwm-working-fan-for-sending-v4 branch > but I get this error: > > $ make W=1 LLVM=1 ARCH=riscv -j16 > CALL scripts/checksyscalls.sh > .pylintrc: warning: ignored by one of the .gitignore files > UPD include/generated/utsversion.h > CC init/version-timestamp.o > KSYMS .tmp_vmlinux0.kallsyms.S > AS .tmp_vmlinux0.kallsyms.o > LD .tmp_vmlinux1 > ld.lld: error: undefined symbol: rust_build_error > referenced by pwm_th1520.4789668fc0b4e501-cgu.0 > drivers/pwm/pwm_th1520.o:(::get_state) in archive vmlinux.a > referenced by pwm_th1520.4789668fc0b4e501-cgu.0 > drivers/pwm/pwm_th1520.o:(::write_waveform) in archive vmlinux.a > referenced by pwm_th1520.4789668fc0b4e501-cgu.0 > drivers/pwm/pwm_th1520.o:(::write_waveform) in archive vmlinux.a > make[2]: *** [scripts/Makefile.vmlinux:91: vmlinux] Error 1 > make[1]: *** [/home/pdp7/linux/Makefile:1241: vmlinux] Error 2 > make: *** [Makefile:248: __sub-make] Error 2 Hi, Thanks for testing ! I can reproduce the issue with your config. The root of the problem was a failing compile time assertion (build_assert!) in the underlying Rust abstracions, I think IoMem since get_state and write_waveform functions are impacted. My development configuration was accidentally hiding this issue, but your configuration correctly exposed it. The kernel config option that is different on my setup is: CONFIG_RUST_BUILD_ASSERT_ALLOW=y Now I have to take a look at the IoMem abstractions, I think there is a new revision [1]. Will apply it and check why exactly compile assertions are triggering. [1] - https://lore.kernel.org/all/20250603-topics-tyr-platform_iomem-v9-0-a27e04157e3e@collabora.com/ > > I've uploaded the config to: > https://protect2.fireeye.com/v1/url?k=0cc1a518-535a9c14-0cc02e57-000babff3563-8df2dfc535042c2a&q=1&e=eaf92127-0b5a-4559-9796-3264da753ae3&u=https%3A%2F%2Fgist.github.com%2Fpdp7%2Fe2c34dd7e4349a54bd67b53254bd3a22 > > Thanks, > Drew > Best regards, -- Michal Wilczynski