From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2222B47884D; Fri, 25 Sep 2026 11:34:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790336096; cv=none; b=pob1TO1mPVdT/4DLURf7lKRZ0ymna+tIGJmt/PbigUjEbHj5+g4H0UQT/CtGt8prnL127i0N0P6FBfkD1aFui/OXh1bHqxbMgVEc+KtUjxhqQ5KzjVh/gpErEjyRxWXMnyidbRg0ePV+6xXyiFlS1KzuyGcZgPBKR0DsGaMZ/Xg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790336096; c=relaxed/simple; bh=o+HfiujomK2MynNig97a+2a2ftn0bwEV8MCv2d9Vdzo=; h=Mime-Version:Content-Type:Date:Message-Id:Subject:Cc:To:From: References:In-Reply-To; b=DwdTPemYDJjTtWda3gy9fHBjB7Cr2uMDu3tF4i5Fk/VbSTzHSodtFzfIoBTyfnXqH+a8kdP3flQ4tKYXqyWLjXUsunyCTOZG44XFY8dUNSwbuj452NcD8T5K83z13lhsvz7zKLi5ujdXZE7trsu4FgG8/6TdMKwPGkt0udhtdls= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LIRvyGNC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LIRvyGNC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3797D1F000FF; Fri, 25 Sep 2026 11:34:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790336094; bh=o+HfiujomK2MynNig97a+2a2ftn0bwEV8MCv2d9Vdzo=; h=Date:Subject:Cc:To:From:References:In-Reply-To; b=LIRvyGNCyp4ct1HfQ70+U3MWqLRteF6Oh+j5Xfa/5NP+yydAwI1nnwiFE1VVb0ghc N72bXDIqBv3Sqsz4MOLKRnBCYRds1Gn/nfP9UskYYaetZEOEqScWDMHjyTYXwSTQSk LfQ+d/qSnZ+F5UJP7/+qA3iiJAwE8hefy7idg/JRrCb5U6WL5LftDWZQVtB/d0U67V F4hE54XTXOq1EUj43hY5/UIIF4In9YZhD85GCBx1SFJ8qvFPhSMvrokjAJfDTrb6K2 OpQQuUdWHOgOPhIbIFNFCqqnIIxB1s09J4iWZ7+p5bGRf2Xp2jsP95EYAHwIDZegOa wNx/lhJhR56qg== Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 25 Sep 2026 13:34:51 +0200 Message-Id: Subject: Re: [PATCH v3] driver core/ACPI: Introduce companion_bus_register() Cc: "Linux Driver Core Development" , "Greg Kroah-Hartman" , "Linux ACPI" , "LKML" , "Michael Kelley" , "Hyper-V List" To: "Rafael J. Wysocki" From: "Danilo Krummrich" References: <12985239.O9o76ZdvQC@rafael.j.wysocki> In-Reply-To: <12985239.O9o76ZdvQC@rafael.j.wysocki> On Fri Sep 25, 2026 at 11:23 AM CEST, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > The ACPI bus type does not allow drivers to be matched to devices, so > the sysfs attributes related to drivers created for it are useless and > their existence is confusing. > > Moreover, it is better to prevent drivers from being registered and > looked up for a bus like that. > > To allow skipping the creation of those sysfs attributes and preventing > driver registration and lookup for the ACPI bus type, introduce a > "companion" bus type concept and add a special registration function > for registering "companion" bus types, companion_bus_register(). > > The "drivers" directory under the ACPI bus type is still needed because > there are versions of systemd that depend on it [1]. Maybe we should also add a brief note above kset_create_and_add("drivers", = ...) why we retain the directory even if !use_drivers. > Link: https://lore.kernel.org/linux-acpi/SN6PR02MB41575266A4580339E186E5D= 9D4812@SN6PR02MB4157.namprd02.prod.outlook.com/ [1] > Signed-off-by: Rafael J. Wysocki Reviewed-by: Danilo Krummrich