From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail11.truemail.it (mail11.truemail.it [217.194.8.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 460702BD59C; Tue, 21 Apr 2026 10:16:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.194.8.81 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776766572; cv=none; b=iioMsDvlb4IqwPRV32Xwql7OvYwqb/+Yrnuf2/SXWzQyG/Z8ITm+6GOeSMFvYl375paNYzYKg5WmDm5KR30kZ5gUmrWMyLvlF5PTCpHMBsG6K/faLyJKc8jhD4sLCFJb35uJ6F8jDu+G/soKwfYxUFaD0uZYnONMHaEXYNwxon4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776766572; c=relaxed/simple; bh=bxxTuMlQOcQt9+SutU5wYexe4SpnFx38EDAqmrj2KxQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iJ5/lXDGyKJOACnW528BF9JIg1mwX6U1+FXLM1jfGlJrTWhCHAHHvMAXDE6uCFvlaXPwxgmtRyCmT93z0mCjvBk9dECKaLQhJPEKQI14x7XcW4p4AINpcQQlpua6jO/vrhU5kGEtEaQ9oe/ZolX/nuE3ek9bzENRlfMEux/pxu0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=dolcini.it; spf=pass smtp.mailfrom=dolcini.it; dkim=pass (2048-bit key) header.d=dolcini.it header.i=@dolcini.it header.b=P9J8Ecxn; arc=none smtp.client-ip=217.194.8.81 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=dolcini.it Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=dolcini.it Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=dolcini.it header.i=@dolcini.it header.b="P9J8Ecxn" Received: from francesco-nb (248.201.173.83.static.wline.lns.sme.cust.swisscom.ch [83.173.201.248]) by mail11.truemail.it (Postfix) with ESMTPA id B5DD01F95F; Tue, 21 Apr 2026 12:16:07 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dolcini.it; s=default; t=1776766568; bh=ui7NLbdFMSE3lMZwZtDMX7zed4AiVYTm9v+0mYYPfQU=; h=From:To:Subject; b=P9J8Ecxn7r34vw3O/E5WLMFUxAdCUuO7e7dYl6fG+/kh0y1CPTiPUhKr3c3Kw5JFh hj4fSbE1SU4lVPjnDiA9E6fYCws79JGv5SWLbtlG3cSWpY6ClYI+NVlORE/fhSH/Ph nlpccaYRhnZwUETDOHydRoTpGEHHPUztO7mCQoc1WLCpNzfEJcaMxI3X4yGVvSF6Zj A2oZONfi78MRLiVvSrbfKo9AbUYcs1OU0NHJmHkSbFqs+4VNOFWT8h1M3C3LV5jM6x CHuZNr1yHeqc//eKkM5lRbEGPw15RRozq7cCEiJFwn/6HrX0z2C7+Va/aBvYYjpHL5 7/9Cq4/O4ccNg== Date: Tue, 21 Apr 2026 12:16:06 +0200 From: Francesco Dolcini To: Krzysztof Kozlowski Cc: Francesco Dolcini , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Mark Brown , Francesco Dolcini , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: Re: [PATCH v1 1/2] dt-bindings: trivial-devices: add toradex,lava-hat-spi Message-ID: <20260421101606.GC23508@francesco-nb> References: <20260420114537.78160-1-francesco@dolcini.it> <20260420114537.78160-2-francesco@dolcini.it> <20260420-task-navy-370ea247fe1d@spud> <005d96ea-b250-4af8-9c5b-d145bae892e5@kernel.org> <20260421083843.GA23508@francesco-nb> <20260421095928.GB23508@francesco-nb> <9c9795b0-a8ba-453d-9a92-f07b3ca59070@kernel.org> Precedence: bulk X-Mailing-List: linux-spi@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: <9c9795b0-a8ba-453d-9a92-f07b3ca59070@kernel.org> On Tue, Apr 21, 2026 at 12:05:45PM +0200, Krzysztof Kozlowski wrote: > On 21/04/2026 11:59, Francesco Dolcini wrote: > > > >> Toradex LAVA hat is way too generic. No, single compatible string is not > >> sufficient, please read writing bindings. > >> > >> Please define exact model and variants. > >> > >>> > >>> The need is to be able to test SPI with a mainline Linux kernel, so I am > >>> looking for a solution that works in mainline Linux. > >> > >> incomplete devices do not stop you from that. > > > > Do this sentence means that I can send a DT file for inclusion in the > > Linux kernel using a compatible documented in incomplete-devices? > > No. You will be testing a mainline DTS + load non-mainline overlay. So > your requirements of "mainline Linux" are fully solved. Overlay is > loaded by bootloader for example and thus your kernel is fully mainline. Ok, I was not clear enough, I am looking to have a solution that is 100% in mainline. > >> But you don't get exceptions because you want to mainline your DTS. Your > >> need detailed hardware description and precise compatible per each exact > >> hat ("exists in multiple variants"). > > > > Let me get into more details here, before sending a new patch version. > > > > We have various LAVA HAT devices, the difference is that they provide > > different features and a different layout, based on the actual carrier > > board they are mated with. > > > > We have an "Aquila LAVA HAT", that can be mated with the "Aquila > > Development Board", and a "Verdin LAVA HAT", that can be mated with a > > "Verdin Dahlia Board". > > Of course, because each device is specific so even the hat must be > specific, unless you have a standard connector like Arduino or RPi. > > > > > As an example, you can find the Verdin Dahlia DTS here, > > ti/k3-am625-verdin-wifi-dahlia.dts, that can be mated with the "Verdin > > LAVA HAT". > > > > The SPI device on both "Aquila LAVA HAT" and "Verdin LAVA HAT", is the > > same, no differences. On the Aquila variant we > > have two instances of it, while on the Verdin we have only one instance > > of it. > > > > So, would we need a compatible like this? > > > > compatible = "toradex,aquila-lava-hat-spi", "toradex,lava-hat-spi"; > > > > or > > > > compatible = "toradex,verdin-lava-hat-spi", "toradex,lava-hat-spi"; > > Yes, assuming that verdin/aquila hat works for EVERY verdin/aquila > board, regardless what SoM or SoC you have there. This is correct, it's exactly like that. > Verdin is a SoM family according to: > https://www.toradex.com/computer-on-modules/verdin-arm-family > > and I doubt you can attach hat to a SoM. There is no connector on SoM > for the hat... so probably you have a board, like Dahlia. Correct, the HAT is for the carrier, and the carrier is for the family. With that clarified I plan to send a v2, with something like "toradex,verdin-dahlia-lava-hat-spi", "toradex,lava-hat-spi" (for each carrier board we have) and DTS files where this is used, and properly documenting the compatibility between the various HW devices. Thanks, Francesco