From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A5EAA3B995B; Thu, 14 May 2026 10:51:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778755917; cv=none; b=hAaAP3smv77uc9uFFoyVRw+LSxSvhDmjulOhyzXTpNraUPV1BXnBUMEVFGh9FJgHFVlq0zqzFcdbzV6boj9uhb7lV1YNLro78lytt66bgYaiGhj/JPKvuzMYyaLjM73YXXJAvdxRTpcuFnMVum7uwfS18mzvui4/ZFJjHwfA8KE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778755917; c=relaxed/simple; bh=NdIUfducvTRfNv9EYak+8ec9D63cIOd0Q93R/5kYsIM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=N6d2bfTUdiZ7dUtyPp3/PnnwseEx+psZvwSA1faVja7mlmRYEbd0q0kdeEu80cj2GaQZxZaVVyyCLqOLMH9e9MtKMCNCksxRPIjk2JiJ55vUZ0pgxUFjYAM9Mop6rHD18vfmsNFNpy+Pet+oisZsgC+y+tkRaxreYd/P2TuZZnc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TZGxBDkP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TZGxBDkP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 114D4C2BCB3; Thu, 14 May 2026 10:51:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778755916; bh=NdIUfducvTRfNv9EYak+8ec9D63cIOd0Q93R/5kYsIM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=TZGxBDkPMRNBmNhF9URVkpubYH9ZVQym8A3/b6mCW61gCl35FjejmAg5Nkv6Wbesg 9cmY4U7pCPnrbZL00Z12bH+ewTJb9/cFganuk7XvB1fUWu8rHs8QiOhEPwJ/S3sD1J EtxFChOpUSfwkLSY+Wr+A9eIYPR4APzdb80ivSay/AYG4yQQQIeQWFvC/8rm3p04J6 u5nVcJhSq0yaTi/3eVimpctCx3HHKDKC8A7us5rTjB76ZWOwuwwMfhFsWkaiHM2cFI /nL/XRo2kj6Ujd6NTPE+y4smsYdL5sRaZqCA9yG2i0baQjIe3lXqw52KSR9DUQr5VI Sg2yPIUvbctJg== X-Mailer: emacs 30.2 (via feedmail 11-beta-1 I) From: Aneesh Kumar K.V To: Greg KH Cc: linux-coco@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Catalin Marinas , Jeremy Linton , Jonathan Cameron , Lorenzo Pieralisi , Mark Rutland , Sudeep Holla , Will Deacon , Steven Price , Suzuki K Poulose Subject: Re: [PATCH v5 0/3] Switch Arm CCA to use an auxiliary device instead of a platform device In-Reply-To: <2026051453-batting-delighted-0a57@gregkh> References: <20260514094030.42495-1-aneesh.kumar@kernel.org> <2026051453-batting-delighted-0a57@gregkh> Date: Thu, 14 May 2026 16:21:48 +0530 Message-ID: Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Greg KH writes: > On Thu, May 14, 2026 at 03:10:27PM +0530, Aneesh Kumar K.V (Arm) wrote: >> As discussed here: >> https://lore.kernel.org/all/20250728135216.48084-12-aneesh.kumar@kernel.org >> >> The general feedback was that a platform device should not be used when >> there is no underlying platform resource to represent. The existing CCA >> support uses a platform device solely to anchor the TSM interface in the >> device hierarchy, which is not an appropriate use of a platform device. >> Use an auxiliary device instead to track CCA support. > > Why an aux device? If this has no platform resources, please use the > faux bus support instead, that is what it is there for. aux devices are > used when you are sharing a real resource among different "child" > drivers, and need some way to coordinate that sharing. If you have no > resources, there's nothing to share, so no need for the complexity that > aux gives you, just use faux instead. > We did discuss between faux an auxiliary devices early here https://lore.kernel.org/all/20251010135922.GC3833649@ziepe.ca To summarize auxiliary device was choosen so that we can do module autoloading. -aneesh