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 AC93E17548; Wed, 4 Jun 2025 18:35:57 +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=1749062157; cv=none; b=DjB97VaOKyHI0pPCqIodqFdI6D5qdmaA78HS7sMdEeMF9CI60Yj59kLQ2XaRrIZX2NsWB9l/jYUGO4r6anJZ6oGm8D3tohx9otP21him8Ui5RHkuXIKcVjvjKLnrN5a2A1I8gROIvcwXpOERY+ZFbz7gz+TL/coSpkVQ6tsUGBQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749062157; c=relaxed/simple; bh=ruxFuBgl/XZhgOubH+/aFTxpJWes37GGmygOmcNMoNo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Q6X+6pRZk8wyVFUvMSp7jj16LkzCjKioomVFYOJj53iv1xxInGmTb1NUxTv3WiipZHxWROXiw5Cxk78KBrEzY/+UyBUSekUgHofJBk2mWSz+NTC4+UJSzHklm5y701G6lzZdlOHIS/qHGP0tgMo6BNgqdBNms4ACL+QU+IgL/zc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=psSJ0WNZ; 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="psSJ0WNZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C0818C4CEE4; Wed, 4 Jun 2025 18:35:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749062157; bh=ruxFuBgl/XZhgOubH+/aFTxpJWes37GGmygOmcNMoNo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=psSJ0WNZSusQYWyAaGTvemScSypcEdHX/aVO7vZ12PU4TdbREOWKpGqQHLRxdb0jL H209cr+0fFNiP54akTL8g0RhDA/DdCDLpE3wnaCRByU6iwnSR/KSUbw1YC6SArfEFI eiifwMyABHxIrSamAf2Kof7vW9eUk9aPD0wZv+n3A9Jsl0tJbRmYMamaOb+6LU5+Id 6AsGc3HwTCKUBVpHLYo/DR5Zk1cFShxMZ8yyPIs4rMkG8NLvX/ACBgLXpLx8cwx0hF MNsUn+RCt7pBn9HBS1WcfQtarIvwQa6A3sUlq+fLVAUZ+RZzkarZPApKBSQQm9rj/3 8DpU8OuijGMew== Message-ID: <49e1e1fc-412d-4334-8337-16e352a34788@kernel.org> Date: Wed, 4 Jun 2025 20:35:51 +0200 Precedence: bulk X-Mailing-List: devicetree-compiler@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/7] dt-bindings: Add support for export-symbols node To: Herve Codina Cc: David Gibson , Andrew Davis , Ayush Singh , Geert Uytterhoeven , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Arnd Bergmann , Greg Kroah-Hartman , Saravana Kannan , devicetree@vger.kernel.org, devicetree-compiler@vger.kernel.org, linux-kernel@vger.kernel.org, Luca Ceresoli , Thomas Petazzoni References: <20250430125154.195498-1-herve.codina@bootlin.com> <20250430125154.195498-2-herve.codina@bootlin.com> <0770a47e-fd2f-4b6f-9a9a-b0d539ace30c@kernel.org> <20250528185740.4bf91bef@bootlin.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 28/05/2025 18:57, Herve Codina wrote: > Hi Krzysztof, > > Thanks a lot for your feedback! > > On Tue, 27 May 2025 20:31:14 +0200 > Krzysztof Kozlowski wrote: > >> On 30/04/2025 14:51, Herve Codina wrote: >>> An export-symbols node allows to export symbols for symbols resolution >>> performed when applying a device tree overlay. >>> >>> When a device tree overlay is applied on a node having an export-symbols >>> node, symbols listed in the export-symbols node are used to resolve >>> undefined symbols referenced from the overlay. >> >> >> I have impression that this is being discussed in three places >> simultaneously - here, DT spec and DT schema. I don't know how to solve >> the multiplication, but I will keep answering here, because that's my part. >> >>> >>> This allows: >>> - Referencing symbols from an device tree overlay without the need to >>> know the full base board. Only the connector definition is needed. >>> >>> - Using the exact same overlay on several connectors available on a given >>> board. >>> >>> For instance, the following description is supported with the >>> export-symbols node: >>> - Base device tree board A: >>> ... >>> foo_connector: connector1 { >>> export-symbols { >>> connector = <&foo_connector>; >>> }; >>> }; >>> >>> bar_connector: connector2 { >>> export-symbols { >>> connector = <&bar_connector>; >>> }; >>> }; >>> ... >> >> And what would this mean? Which symbol is exported - foo or bar? > > Symbols are exported only when an overlay is applied on the node where the > export-symbols node is available. Those symbols are visible only from the > overlay applied. Symbols exported thanks to export-symbols are not global > to the all device-tree (it is not __symbols__) but local to a node. > > If an overlay is applied at connector1 node, it can use the 'connector' > symbols and thanks to export-symbols, the 'connector' symbol will be > resolved to foo_connector. > > If the overlay is applied at connector2 node, the 'connector' symbol is then > resolved to bar_connector. OK, this explains a lot. Unless I missed it, would be nice to include it in binding description. ... ... >>> +patternProperties: >>> + "^[a-zA-Z_]?[a-zA-Z0-9_]*$": >> >> This messes up with coding style which I would prefer keep intact. >> Basically these properties will be using label style. > > Yes, those properties remap phandles. > > Their names are the name of the label used from the overlay and their > values are the phandle mapped. > > You already have this kind properties using label style in __symbols__, > __fixups__, __local_fixups__ nodes. I have them in DTB, but I don't have these in DTS. The exported-symbols would be in the DTS and that is what coding style is about. Best regards, Krzysztof