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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 CEF26CD4851 for ; Thu, 14 May 2026 12:45:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vupuZrldNnISyodqZgietZ5rJGgmjJeY1/v9Vsj3aVQ=; b=EEpsNDzJIoBiGKiAghaZAzUJzA fTMk+bAWzNVUcd4LuTRDC4EpLnzpw3M+5XhXZuBG3sTAJwxA8N0D1/O++R7jEbCmwaYSOmdKdesj6 HELG7ysNcFQgiv6ad838JTH8lO+5/Ltou0l8lbogNah2ul1RTuVVee5yP664YQTdSkk+KAElL7Z5O xuQn/qS2SXZsYf6x3Ptq88wuC3g0nZR209Ceakq0zRXF6M40dA7zJFR4LnuSls78029c03t8nPPK3 s37GmK4aJPfgZqdP5uLplKgWBEu/YVX51si2+BZ6o+ruckL6mB9+DmR/R86ZQ7FzS92/z0cyg5Jjk 1Klw3DbA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wNVRn-00000005V6p-1vAl; Thu, 14 May 2026 12:45:51 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wNVRk-00000005V5D-3nMl for linux-arm-kernel@lists.infradead.org; Thu, 14 May 2026 12:45:49 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id EA36760132; Thu, 14 May 2026 12:45:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2AA80C2BCB8; Thu, 14 May 2026 12:45:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778762747; bh=uzxXH31tSj4V03e2tHyrBCneawBM4/arZJhlthRiRYI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Kq8O/dxE1+71TBvjywPOqVDLIbXE4IJFQdg8x5tDelx2tpCYRMyYlo8lumZYHjVjo KjL98x8TbAqLzoIgLbIxH6ZZEZp8jsjxuGHjBY/TZ6n15Hzr1b+nrwii87ACxwb5KU Vx4hjQUndhL6IjLRM9AJ0+z7cLTD1fLTuONURu5w= Date: Thu, 14 May 2026 14:45:52 +0200 From: Greg KH To: "Aneesh Kumar K.V" 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 Message-ID: <2026051428-untaxed-slacking-d029@gregkh> References: <20260514094030.42495-1-aneesh.kumar@kernel.org> <2026051453-batting-delighted-0a57@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, May 14, 2026 at 04:21:48PM +0530, Aneesh Kumar K.V wrote: > 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. That's not a valid reason to use the aux driver, sorry. If you have hardware that triggers an auto-module-load, then this is really a hardware driver. If it is a "virtual" driver like this, then you need to explicitly load it on your own. Don't abuse apis for reasons that they are not designed for. thanks, greg k-h