From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A99E3E6E7F4 for ; Tue, 3 Feb 2026 10:39:11 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C8EED10E5FE; Tue, 3 Feb 2026 10:39:10 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="SgnwILfk"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id D94D710E5FE for ; Tue, 3 Feb 2026 10:39:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1770115148; bh=7p06UjiOAmOZZ+ivGAxqutS8zWb3kS0ttTynLQr7ZJc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=SgnwILfkwv3oTBP0QRGD4+/0u2LFd1lrBTYwrzMVWZl6IZzITGNDJPHWmpbkEnt4e TG4wDLMOmMtMS+ETjG6JC5bdL406D0GAmvytUj51hwLYcWrpJPbM5WTaSzTywjZoaI FFxjHM3rtDg9gcYE5FzA2bwwRKFt6LBt2jw+GX4PnHvoBw12en8RgzxwQBy1kOgZVQ ZA5lrnb2dyhfKzBwd5uelfXNfqKGTSm7/ZR+xlRsCWRuBbQbKZuf01ZH6deeTiX1ux r5u/L67j38Vt5bqXFK0YhNrmJ6Nmb6FQGbO7oT3YpnxoEZDA9Y6OsNWS5net3YeuS/ 04UbIXZpqpNlw== Received: from fedora (unknown [IPv6:2a01:e0a:2c:6930:d919:a6e:5ea1:8a9f]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id 45D4217E00A3; Tue, 3 Feb 2026 11:39:07 +0100 (CET) Date: Tue, 3 Feb 2026 11:39:02 +0100 From: Boris Brezillon To: Alice Ryhl Cc: Maxime Ripard , Daniel Almeida , "Rafael J. Wysocki" , Viresh Kumar , Danilo Krummrich , Maarten Lankhorst , Thomas Zimmermann , David Airlie , Simona Vetter , Drew Fustini , Guo Ren , Fu Wei , "Uwe =?UTF-8?B?S2xlaW5l?= =?UTF-8?B?LUvDtm5pZw==?=" , Michael Turquette , Stephen Boyd , Miguel Ojeda , Boqun Feng , Gary Guo , "=?UTF-8?B?QmrDtnJu?= Roy Baron" , Benno Lossin , Andreas Hindborg , Trevor Gross , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-riscv@lists.infradead.org, linux-pwm@vger.kernel.org, linux-clk@vger.kernel.org, rust-for-linux@vger.kernel.org Subject: Re: [PATCH v3 1/3] rust: clk: use the type-state pattern Message-ID: <20260203113902.501e5803@fedora> In-Reply-To: References: <20260107-clk-type-state-v3-0-77d3e3ee59c2@collabora.com> <20260107-clk-type-state-v3-1-77d3e3ee59c2@collabora.com> <20260108-delectable-fennec-of-sunshine-ffca19@houat> <98CD0BF6-3350-40B9-B8A9-F569AE3E3220@collabora.com> <20260119-thundering-tested-robin-4be817@houat> Organization: Collabora X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, 19 Jan 2026 12:35:21 +0000 Alice Ryhl wrote: > On Mon, Jan 19, 2026 at 11:45:57AM +0100, Maxime Ripard wrote: > > On Thu, Jan 08, 2026 at 11:14:37AM -0300, Daniel Almeida wrote: > > > > For example, it's quite typical to have (at least) one clock for the bus > > > > interface that drives the register, and one that drives the main > > > > component logic. The former needs to be enabled only when you're > > > > accessing the registers (and can be abstracted with > > > > regmap_mmio_attach_clk for example), and the latter needs to be enabled > > > > only when the device actually starts operating. > > > > > > > > You have a similar thing for the prepare vs enable thing. The difference > > > > between the two is that enable can be called into atomic context but > > > > prepare can't. > > > > > > > > So for drivers that would care about this, you would create your device > > > > with an unprepared clock, and then at various times during the driver > > > > lifetime, you would mutate that state. > > The case where you're doing it only while accessing registers is > interesting, because that means the Enable bit may be owned by a local > variable. We may imagine an: > > let enabled = self.prepared_clk.enable_scoped(); > ... use registers > drop(enabled); > > Now ... this doesn't quite work with the current API - the current > Enabled stated owns both a prepare and enable count, but the above keeps > the prepare count in `self` and the enabled count in a local variable. > But it could be done with a fourth state, or by a closure method: > > self.prepared_clk.with_enabled(|| { > ... use registers > }); > > All of this would work with an immutable variable of type Clk. Hm, maybe it'd make sense to implement Clone so we can have a temporary clk variable that has its own prepare/enable refs and releases them as it goes out of scope. This implies wrapping *mut bindings::clk in an Arc<> because bindings::clk is not ARef, but should be relatively easy to do. Posting the quick experiment I did with this approach, in case you're interested [1] [1]https://gitlab.freedesktop.org/bbrezillon/linux/-/commit/d5d04da4f4f6192b6e6760d5f861c69596c7d837