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 BB4554A204F; Tue, 6 Oct 2026 18:50:40 +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=1791312641; cv=none; b=r6/CN570K4Y7YcnyPI3WNut85xh3PYxLgE8nHvyCPXSF2p6pPBwO3qj9n4w1fAMTJCplOSktUULfjv4iAQSnqEryfexhuKssdqmh7jTOWmj/+pXpUoDLs8W8DN6xlQfeaDhzkH+C2HIPcGerbb3AoYKhaOklkBk/j2/KSVqWySE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791312641; c=relaxed/simple; bh=pAafaC7hBrqDElAgMvcvE6thWpIPEbnhcZP2tU/+WTg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=IHjiR5Bs+pMNn9g3bn69LnXfUIrgY9Vnkjv3jgG79Sv737EtQ7V2/g4ldj9zRZgyjeMYnRhapkX+ZhQHaalRqEMRlWnLHrz2rRsnngiSQioK+7Z9mqk0YyuMrKm+CoKL1sdqR0pfkpGgokzbHhCe0MwOBAiubmo3L/I0FqcUXjQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nqVtH0PD; 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="nqVtH0PD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 258821F0089B; Tue, 6 Oct 2026 18:50:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791312640; bh=tXLSbpyUG31gTT+jrU2zP+FXGyzeEv4VmzVE/LaXxjY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=nqVtH0PDsADZHitSsB9NWX6JfSdnbWpCkPis74u/0eQ63jKclvt5x9BouQeAL7kPr 8ZusnzhuwxM4EYc3SKaoCz3/Qn3ZujK5jHZtdB3Smo+GYoy+pVIXJtUzesjicm7FC2 MEmscX1QmXDyp9yR/DlINPPGfK6bwhEccUyN68rL4c+Nm9IBGK4MA69p/6wLDZGTdF nQXottDid1ozi9tFP6Jli6w//JVcmnFjNThZ5LaTmMuv+kwLLrjQW+bFTIZBRLgMWK WjclFiJq1gqZGf13rs3vSt7mU51/uVUG4sBUKYEnJEsmJfKiJf7KA2EerfDEQjyXOs ZRZJ0xUdNzSdA== Date: Tue, 6 Oct 2026 13:50:39 -0500 From: Rob Herring To: Yureka Lilian Cc: Michael Reeves , Sven Peter , Janne Grunau , Neal Gompa , Jassi Brar , Krzysztof Kozlowski , Conor Dooley , Hector Martin , "Joerg Roedel (AMD)" , Will Deacon , Robin Murphy , Dmitry Torokhov , Jiri Kosina , Benjamin Tissoires , asahi@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, iommu@lists.linux.dev, linux-input@vger.kernel.org, Julian Braha , Sasha Finkelstein Subject: Re: [PATCH v4 04/10] dt-bindings: input: apple: Add DockChannel HID transport Message-ID: <20261006185039.GE2194299-robh@kernel.org> References: <20260925-apple-mtp-keyboard-final-v4-0-304c267518f4@gmail.com> <20260925-apple-mtp-keyboard-final-v4-4-304c267518f4@gmail.com> <20261006160049.GA2406717-robh@kernel.org> <2687bc3e-b73a-415c-8c68-8249e1fe4e6b@cyberchaos.dev> Precedence: bulk X-Mailing-List: linux-kernel@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: <2687bc3e-b73a-415c-8c68-8249e1fe4e6b@cyberchaos.dev> On Tue, Oct 06, 2026 at 08:09:47PM +0200, Yureka Lilian wrote: > > On 10/6/26 18:00, Rob Herring wrote: > > On Fri, Sep 25, 2026 at 10:09:31PM +1000, Michael Reeves wrote: > > [...] > > > + > > > + mboxes: > > > + items: > > > + - description: ASC mailbox used for RTKit control > > > + - description: DockChannel FIFO mailbox used for HID packets > > > + > > > + mbox-names: > > > + items: > > > + - const: asc > > > + - const: dockchannel > > > + > > > + iommus: > > > + maxItems: 1 > > > + > > > + stm: > > > + type: object > > > + description: > > > + STM interface providing the vendor, product and version identifiers > > > + and serial number shared by the HID devices. When present, the host > > > + must query this interface before registering the keyboard. > > > + additionalProperties: false > > An empty node is unusual. Why can't you just query the STM interface and > > treat it not existing or having those properties the same as no 'stm' > > node. > > The issue is there is no indicator for the stm *not* being present: We boot > the MTP coprocessor, and then receive a message when the stm is available. > In that case we know it's ready and we can proceed with obtaining the serial > numbers and registering the hid devices. But if there is no stm, we simply > do not get the stm ready message, and the hid devices are never registered > (this is the case in the original downstream Asahi dockchannel-hid). To make > the stm optional *without* taking the information from the device tree, this > would require some sort of timeout for waiting for the stm ready message. I > outlined the available options in this thread[1] and argued the empty stm > subnode makes sense, since this is describing a peripheral which may or may > not be present (and this information is useful to initialize the device > properly). > > Link[1]: https://lore.kernel.org/asahi/bbaca769-312c-4a24-9524-16cb2b4f277f@cyberchaos.dev/ Okay, but you don't need a node here. Just an 'apple,has-stm' or similar property will suffice. Rob