From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 575C23033FB; Tue, 4 Aug 2026 12:26:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785846412; cv=none; b=qW/AIGBFnxsy8lLF91AVpnjhTo/TBqviOBiaMA2iGoAfT7HGCQc0ZJbl210WS+HID9o9nKIwK2w+a5VIHRHlcvTEXu4kL5oxqa1AJeduwYPx2vcBA4u8mhi2ls8FGcal+MYmMcB+Dt8t0KJhiOeDQC8reoUZ0+U1TDkffoEPnRg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785846412; c=relaxed/simple; bh=CIsOcSZCewxuRWrvNu5o7YPTP1SaaWyKIrQd6nnzQGc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=APzauKwqWAI/E3pI2JMcsY44Gcf16eYpVEKKI3olptP1O0XsF2ilMOZzMmwO12OMsCNTFmVZkOWS0uRGVQ8dk8puyNBETVBCkS8Kgc3Hug+nCE3luNx/8XLxFWpgF3MQqR9Y3N4n2FO8zTff+8X4ut5fB7GCbs9B2irz0Zy34mY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=rdeXvjAL; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="rdeXvjAL" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 99A831476; Tue, 4 Aug 2026 05:26:45 -0700 (PDT) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 420813F66F; Tue, 4 Aug 2026 05:26:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1785846409; bh=CIsOcSZCewxuRWrvNu5o7YPTP1SaaWyKIrQd6nnzQGc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rdeXvjALc5P08CCMWdpwpyu5PRruugZhG1Xvm9uVtHOFvTMfGg+V6W6T/KiyyYlUt wOQLJQbZHZMR/zuB0JteLez8DYdJLuzXMr9gl++Sdk/0aysmW+4qeZ91MXNrLBSMVO enn79nzimhnI5kZq8RXFPtCb8YQ/J9mbVABirUCw= Date: Tue, 4 Aug 2026 14:26:37 +0200 From: Beata Michalska To: Alice Ryhl Cc: ojeda@kernel.org, dakr@kernel.org, gregkh@linuxfoundation.org, rafael@kernel.org, boqun@kernel.org, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, tmgross@umich.edu, daniel.almeida@collabora.com, boris.brezillon@collabora.com, work@onurozkan.dev, samitolvanen@google.com, rust-for-linux@vger.kernel.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH v2 2/3] rust: platform: wire runtime PM callbacks Message-ID: References: <20260721153617.869933-1-beata.michalska@arm.com> <20260721153617.869933-3-beata.michalska@arm.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Aug 04, 2026 at 08:02:11AM +0000, Alice Ryhl wrote: > On Tue, Jul 21, 2026 at 05:34:03PM +0200, Beata Michalska wrote: > > Allow Rust platform drivers to expose runtime PM callbacks to the driver core. > > > > The runtime PM abstraction builds a dev_pm_ops table for the concrete driver > > implementation, but the platform bus still needs to receive that table through > > struct platform_driver. Add an optional PM_OPS associated constant to > > platform::Driver and initialize the coresponding C device_driver struct > > accordingly during registration. The platform glue only wires the callback > > table into the C driver model; ownership of the callback payload and > > runtime PM teardown remain with the pm module. > > > > Signed-off-by: Beata Michalska > > --- > > rust/kernel/platform.rs | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs > > index d8d48f60b0b9..b7e422388634 100644 > > --- a/rust/kernel/platform.rs > > +++ b/rust/kernel/platform.rs > > @@ -72,6 +72,11 @@ unsafe fn register( > > None => core::ptr::null(), > > }; > > > > + let pm_ops = match T::PM_OPS { > > + Some(ops) => ops, > > + None => core::ptr::null(), > > + }; > > This value is just any user-provided &bindings::pm_ops, which I think is > too lax. There is no guarantee that the Registration and the PM_OPS > table agree on what the type T is, which can lead to type confusion. > Indeed, as stated in the commit message > Most likely, you must instead give `trait Driver` an associated type > saying "the PmOps type is this particular type", and then here you can > do `Some(T::PM_OPS)` to actually get the associated table. > > And then in the registration, you can further require that the types > also match there. E.g., maybe make the registration generic over the > Driver type and then the inner type T is just D::PmData or similar. > I do need to ponder on that one a bit. --- BR Beata > Alice > > > // SAFETY: It's safe to set the fields of `struct platform_driver` on initialization. > > unsafe { > > (*pdrv.get()).driver.name = name.as_char_ptr(); > > @@ -79,6 +84,7 @@ unsafe fn register( > > (*pdrv.get()).remove = Some(Self::remove_callback); > > (*pdrv.get()).driver.of_match_table = of_table; > > (*pdrv.get()).driver.acpi_match_table = acpi_table; > > + (*pdrv.get()).driver.pm = pm_ops; > > } > > > > // SAFETY: `pdrv` is guaranteed to be a valid `DriverType`. > > @@ -222,6 +228,9 @@ pub trait Driver { > > /// The table of ACPI device ids supported by the driver. > > const ACPI_ID_TABLE: Option> = None; > > > > + /// Runtime PM callbacks > > + const PM_OPS: Option<&'static bindings::dev_pm_ops> = None; > > + > > /// Platform driver probe. > > /// > > /// Called when a new platform device is added or discovered. > > -- > > 2.43.0 > >