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 84B2FCD6E6B for ; Fri, 5 Jun 2026 09:12:14 +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:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=d7e/64Lm4FJCHnz40nUrkUeXHtudnHaWROVmMiFI1MM=; b=evg7h5FAGwNAhug0NOh3BQrHCT ZI690f4kKS61f+1iwhvo1/O0LbxKVKnOZHA2ZqfDPl8infQ9iEd5GLUODZInJmlRgXbRCPLp+wA04 dIJBTxqCZNf3zUmineWGXXvBmUph0jdeJvBBhwoFrgpU7jQzTZ0vHQC0L5IxOrTtquxc5GxhGW5CF 1Uz1ny+KXQaX1pesqOTOJiN4sab+uSf0qotFeNtXoEqXq6ZfdlVXl8WzOPz1Z9xdW9bbeTHdcCnDL V+eOZsyYi77tWxxFHMR90FcbcpJQgvfHJKJvnw9GceMvfbUReFjt0ukgUmt9r695FNvf+3z9XigNi Exiz+JBg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wVQb1-00000000NVT-2dzZ; Fri, 05 Jun 2026 09:12:07 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wVQaz-00000000NVM-3IpE for linux-arm-kernel@lists.infradead.org; Fri, 05 Jun 2026 09:12:05 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 3F1854371C; Fri, 5 Jun 2026 09:12:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29CA11F00893; Fri, 5 Jun 2026 09:11:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780650725; bh=d7e/64Lm4FJCHnz40nUrkUeXHtudnHaWROVmMiFI1MM=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=b4jjUShMkrkAmKNxKHC+rOncDO9lTBGvhVgQKmVj7x8ATGjGdsoqadL19HOJzjcxR abVTB3dLsl7EZQ2p2CPYahFdM4sgLY65GgoMHPZuL7sb7PSbwBdnznsIqcbMKnMOjt XTHTs1ZE4p3L6MxoST7yq0c+wxGMdPmtJwK2TMfXoZIljRBthAQ2h7zEsml9KWCxdL dAdzswtSkYkPB7Psqhpere9y5gLq0e8V2bg3fS7jUTi6jVBsAsuPxhlt5P48hVgeez rbz/xNkuNK7+DyNURO2sbUzqDd9qW8Gmmk+yn9qr9o/aSVbwXaRdOnaOWse3qXTmgc K3bZT7ZX4PBGg== Message-ID: <8387afa5-f2d9-4006-a1c9-d2122ea6245d@kernel.org> Date: Fri, 5 Jun 2026 11:11:55 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/5] dt-bindings: connector: Add fsl,io-connector binding To: Frank Li Cc: "Chancel Liu (OSS)" , Chancel Liu , "robh@kernel.org" , "krzk+dt@kernel.org" , "conor+dt@kernel.org" , "s.hauer@pengutronix.de" , "festevam@gmail.com" , "mturquette@baylibre.com" , "sboyd@kernel.org" , "kernel@pengutronix.de" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "imx@lists.linux.dev" , "linux-arm-kernel@lists.infradead.org" , "linux-clk@vger.kernel.org" References: <20260519-macho-degu-from-nibiru-960af2@quoll> <74eb56fb-546d-4b2c-9bbc-01a40937f5d3@kernel.org> <8046287e-87a2-4d18-ad3d-248620a752a9@kernel.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; keydata= xsFNBFVDQq4BEAC6KeLOfFsAvFMBsrCrJ2bCalhPv5+KQF2PS2+iwZI8BpRZoV+Bd5kWvN79 cFgcqTTuNHjAvxtUG8pQgGTHAObYs6xeYJtjUH0ZX6ndJ33FJYf5V3yXqqjcZ30FgHzJCFUu JMp7PSyMPzpUXfU12yfcRYVEMQrmplNZssmYhiTeVicuOOypWugZKVLGNm0IweVCaZ/DJDIH gNbpvVwjcKYrx85m9cBVEBUGaQP6AT7qlVCkrf50v8bofSIyVa2xmubbAwwFA1oxoOusjPIE J3iadrwpFvsZjF5uHAKS+7wHLoW9hVzOnLbX6ajk5Hf8Pb1m+VH/E8bPBNNYKkfTtypTDUCj NYcd27tjnXfG+SDs/EXNUAIRefCyvaRG7oRYF3Ec+2RgQDRnmmjCjoQNbFrJvJkFHlPeHaeS BosGY+XWKydnmsfY7SSnjAzLUGAFhLd/XDVpb1Een2XucPpKvt9ORF+48gy12FA5GduRLhQU vK4tU7ojoem/G23PcowM1CwPurC8sAVsQb9KmwTGh7rVz3ks3w/zfGBy3+WmLg++C2Wct6nM Pd8/6CBVjEWqD06/RjI2AnjIq5fSEH/BIfXXfC68nMp9BZoy3So4ZsbOlBmtAPvMYX6U8VwD TNeBxJu5Ex0Izf1NV9CzC3nNaFUYOY8KfN01X5SExAoVTr09ewARAQABzSVLcnp5c3p0b2Yg S296bG93c2tpIDxrcnprQGtlcm5lbC5vcmc+wsGVBBMBCgA/AhsDBgsJCAcDAgYVCAIJCgsE FgIDAQIeAQIXgBYhBJvQfg4MUfjVlne3VBuTQ307QWKbBQJoF1BKBQkWlnSaAAoJEBuTQ307 QWKbHukP/3t4tRp/bvDnxJfmNdNVn0gv9ep3L39IntPalBFwRKytqeQkzAju0whYWg+R/rwp +r2I1Fzwt7+PTjsnMFlh1AZxGDmP5MFkzVsMnfX1lGiXhYSOMP97XL6R1QSXxaWOpGNCDaUl ajorB0lJDcC0q3xAdwzRConxYVhlgmTrRiD8oLlSCD5baEAt5Zw17UTNDnDGmZQKR0fqLpWy 786Lm5OScb7DjEgcA2PRm17st4UQ1kF0rQHokVaotxRM74PPDB8bCsunlghJl1DRK9s1aSuN hL1Pv9VD8b4dFNvCo7b4hfAANPU67W40AaaGZ3UAfmw+1MYyo4QuAZGKzaP2ukbdCD/DYnqi tJy88XqWtyb4UQWKNoQqGKzlYXdKsldYqrLHGoMvj1UN9XcRtXHST/IaLn72o7j7/h/Ac5EL 8lSUVIG4TYn59NyxxAXa07Wi6zjVL1U11fTnFmE29ALYQEXKBI3KUO1A3p4sQWzU7uRmbuxn naUmm8RbpMcOfa9JjlXCLmQ5IP7Rr5tYZUCkZz08LIfF8UMXwH7OOEX87Y++EkAB+pzKZNNd hwoXulTAgjSy+OiaLtuCys9VdXLZ3Zy314azaCU3BoWgaMV0eAW/+gprWMXQM1lrlzvwlD/k whyy9wGf0AEPpLssLVt9VVxNjo6BIkt6d1pMg6mHsUEVzsFNBFVDXDQBEADNkrQYSREUL4D3 Gws46JEoZ9HEQOKtkrwjrzlw/tCmqVzERRPvz2Xg8n7+HRCrgqnodIYoUh5WsU84N03KlLue MNsWLJBvBaubYN4JuJIdRr4dS4oyF1/fQAQPHh8Thpiz0SAZFx6iWKB7Qrz3OrGCjTPcW6ei OMheesVS5hxietSmlin+SilmIAPZHx7n242u6kdHOh+/SyLImKn/dh9RzatVpUKbv34eP1wA GldWsRxbf3WP9pFNObSzI/Bo3kA89Xx2rO2roC+Gq4LeHvo7ptzcLcrqaHUAcZ3CgFG88CnA 6z6lBZn0WyewEcPOPdcUB2Q7D/NiUY+HDiV99rAYPJztjeTrBSTnHeSBPb+qn5ZZGQwIdUW9 YegxWKvXXHTwB5eMzo/RB6vffwqcnHDoe0q7VgzRRZJwpi6aMIXLfeWZ5Wrwaw2zldFuO4Dt 91pFzBSOIpeMtfgb/Pfe/a1WJ/GgaIRIBE+NUqckM+3zJHGmVPqJP/h2Iwv6nw8U+7Yyl6gU BLHFTg2hYnLFJI4Xjg+AX1hHFVKmvl3VBHIsBv0oDcsQWXqY+NaFahT0lRPjYtrTa1v3tem/ JoFzZ4B0p27K+qQCF2R96hVvuEyjzBmdq2esyE6zIqftdo4MOJho8uctOiWbwNNq2U9pPWmu 4vXVFBYIGmpyNPYzRm0QPwARAQABwsF8BBgBCgAmAhsMFiEEm9B+DgxR+NWWd7dUG5NDfTtB YpsFAmgXUF8FCRaWWyoACgkQG5NDfTtBYptO0w//dlXJs5/42hAXKsk+PDg3wyEFb4NpyA1v qmx7SfAzk9Hf6lWwU1O6AbqNMbh6PjEwadKUk1m04S7EjdQLsj/MBSgoQtCT3MDmWUUtHZd5 RYIPnPq3WVB47GtuO6/u375tsxhtf7vt95QSYJwCB+ZUgo4T+FV4hquZ4AsRkbgavtIzQisg Dgv76tnEv3YHV8Jn9mi/Bu0FURF+5kpdMfgo1sq6RXNQ//TVf8yFgRtTUdXxW/qHjlYURrm2 H4kutobVEIxiyu6m05q3e9eZB/TaMMNVORx+1kM3j7f0rwtEYUFzY1ygQfpcMDPl7pRYoJjB dSsm0ZuzDaCwaxg2t8hqQJBzJCezTOIkjHUsWAK+tEbU4Z4SnNpCyM3fBqsgYdJxjyC/tWVT AQ18NRLtPw7tK1rdcwCl0GFQHwSwk5pDpz1NH40e6lU+NcXSeiqkDDRkHlftKPV/dV+lQXiu jWt87ecuHlpL3uuQ0ZZNWqHgZoQLXoqC2ZV5KrtKWb/jyiFX/sxSrodALf0zf+tfHv0FZWT2 zHjUqd0t4njD/UOsuIMOQn4Ig0SdivYPfZukb5cdasKJukG1NOpbW7yRNivaCnfZz6dTawXw XRIV/KDsHQiyVxKvN73bThKhONkcX2LWuD928tAR6XMM2G5ovxLe09vuOzzfTWQDsm++9UKF a/A= In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 03/06/2026 00:18, Frank Li wrote: > On Mon, May 25, 2026 at 02:28:32PM +0200, Krzysztof Kozlowski wrote: >> On 25/05/2026 08:26, Chancel Liu (OSS) wrote: >>>>>>>>>>>>> +description: >>>>>>>>>>>>> + The NXP I/O connector represents a physically present I/O >>>>>>>>>>>>> +connector on the >>>>>>>>>>>>> + base board. It acts as a nexus that exposes a constrained >>>>>>>>>>>>> +set >>>>>>>> of >>>>>>>>>>>>> +I/O >>>>>>>>>>>>> + resources, such as GPIOs, clocks, PWMs and interrupts, >>>>>>>>>>>>> +through fixed >>>>>>>>>>>>> + electrical wiring. All actual hardware providers reside on >>>>>>>>>>>>> +the >>>>>>>> base >>>>>>>>>> board. >>>>>>>>>>>>> + The connector node only defines index-based mappings to >>>>>>>>>>>>> + those >>>>>>>>>>>> providers. >>>>>>>>>>>>> + >>>>>>>>>>>>> +properties: >>>>>>>>>>>>> + compatible: >>>>>>>>>>>>> + const: fsl,io-connector >>>>>>>>>>>> >>>>>>>>>>>> Everything is IO. Everything is connector, so your compatible >>>>>>>>>>>> does not match requirements from writing bindings. >>>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> Yes, this compatible is too generic. I will rename the >>>>>>>>>>> compatible to fsl,aud-io-connector. >>>>>>>>>> >>>>>>>>>> aud is not much better. Which boards have it? What's the pinout? >>>>>>>> What's >>>>>>>>>> standard? Is it described anywhere? If so, provide reference to >>>>>>>> spec/docs. >>>>>>>>>> >>>>>>>>> >>>>>>>>> This is not an industry standard electrical interface. This >>>>>>>>> connector >>>>>>>> >>>>>>>> Then if you do not have standard, then you have board specific >>>>>>>> layouts thus you need board-specific compatibles. You can use >>>>>>>> fallbacks. Generic fallback could work, but both io-connector and >>>>>>>> aud-io-connector are just too generic. Every connector is >>>>>>>> "connector" and "io", thus absolutely anything can be >>>>>>>> "io-connector". "aud" improves it only a bit, thus honestly I would >>>> go with board specific fallback as well. >>>>>>>> >>>>>>> >>>>>>> How about board specific + common fallback compatible like this: >>>>>>> compatible: >>>>>>> items: >>>>>>> - enum: >>>>>>> - fsl,imx95-19x19-evk-aud-io-connector >>>>>>> - fsl,imx952-evk-aud-io-connector >>>>>>> - const: fsl,imx-aud-io-connector Since the daughter board is >>>>>>> named “IMX-AUD-IO” in publicly available >>>>>> >>>>>> I don't think it is named like that. >>>>>> >>>>>> git grep -i imx-aud-io >>>>>> >>>>>>> documentation, common compatible clearly indicates that this >>>>>>> connector is intended for that. >>>>>>> >>>>>>> Also, I want to talk about the topic of generic connector. It's a >>>>>>> common design that daughter board is connected to base board through >>>>>>> a connector. This connector more often acts as a nexus that exposes >>>>>>> a constrained subset of GPIO, clock, PWM and interrupt resources to >>>>>>> the daughter board. Can we document this kind of connector as a >>>>>>> generic binding? >>>>>> >>>>>> So this binding is the connector between carrier and some addon? Then >>>>>> you don't get a compatible for that at all, because it is not >>>>>> necessary, not useful and NEVER used. Do you see socket LGA "connector" >>>> bindings? No. >>>>> >>>>> Not exactly. Any connector connects a carrier board with an add-on >>>> board. >>>>> The key point here is that this connector type is reused across >>>>> different boards, even though it is not an industry-standard >>>>> connector. Both the signal definitions and the mechanical layout are >>>> defined. >>>>> >>>>> The same add-on boards can therefore be reused across different base >>>>> boards that use this type of connector. >>>>> >>>>> There are also GPIO mappings involved. For example, pin 1 on the >>>>> connector may represent reset-gpios, but it could be connected to >>>>> GPIO0 on board A and GPIO1 on board B. >>>>> >>>>> Without a connector definition layer, this would create an N × M >>>>> combination problem. The Nexus node discussion already covered this >>>> topic: >>>>> https://osseu2025.sched.com/event/25Vrw >>>>> >>>>> An LGA socket is a CPU socket, where the signals are completely >>>>> transparent to software, so it is not a good comparison. A PCIe M.2 >>>>> Key-M/E connector would be a more appropriate comparison. >>>>> >>>> >>>> So the terminology of daughter and carrier boards was confusing. If this >>>> is a hat, mezzanine or other addon, it's fine. >>>> >>> >>> The IMX-AUD-IO is an add-on board that attaches to the base board. To >>> make it clearer, I will replace "daughter board" with "add-on board" >>> throughout descriptions. >>> >>>> I still insist on board specific compatibles - fallback and specific. >>>> >>> >>> The base board has a slot component that is mechanically compatible >>> with a PCIe x8 connector. However, it carries no PCIe signals and the >>> pins are repurposed to carry fixed board-level audio I/O related >>> signals. >>> >>> I think we can name a compatible reflects a standard mechanical form >>> factor. >>> For the compatibles (specific + fallback) I propose: >>> - enum: >>> - fsl,imx95-19x19-evk-aud-io-pcie-x8-slot >>> - fsl,imx952-evk-aud-io-pcie-x8-slot >>> - const: fsl,aud-io-pcie-x8-slot >> >> Does not solve my request, so I won't ack it. Maybe you will get ack >> from other DT maintainer then. > > Krzysztof: > Thank you for your support. This type header/slot is difficult to > name it. > > After read again previous comments > > "Then if you do not have standard, then you have board specific layouts > thus you need board-specific compatibles. You can use fallbacks. Generic > fallback could work, but both io-connector and aud-io-connector are just > too generic. Every connector is "connector" and "io", thus absolutely > anything can be "io-connector". "aud" improves it only a bit, thus > honestly I would go with board specific fallback as well." > > Do you means > oneOf > - items: > - enum: > - fsl,imx943-evk-aud-io-pcie-x8-slot > - fsl,imx952-evk-aud-io-pcie-x8-slot > - const: fsl,imx95-19x19-evk-aud-io-pcie-x8-slot > - const: fsl,imx95-19x19-evk-aud-io-pcie-x8-slot Yes, could be a bit shorter like fsl,imx95-19x19-evk-aud-io-slot or even without slot because prefixing it with board compatible makes it very specific. > > Frank > >> >> Best regards, >> Krzysztof Best regards, Krzysztof