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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85DB1C77B73 for ; Wed, 19 Apr 2023 07:13:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232040AbjDSHNm (ORCPT ); Wed, 19 Apr 2023 03:13:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230153AbjDSHNh (ORCPT ); Wed, 19 Apr 2023 03:13:37 -0400 Received: from relay1-d.mail.gandi.net (relay1-d.mail.gandi.net [217.70.183.193]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82A4B469A; Wed, 19 Apr 2023 00:13:35 -0700 (PDT) Received: from booty (unknown [77.244.183.192]) (Authenticated sender: luca.ceresoli@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 31FB5240002; Wed, 19 Apr 2023 07:13:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1681888414; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RTPr0qXgUAiaKYOz5+LueWThu8nf5uFWHeafU8Tagso=; b=fudy4vON3s+meeKECVU7GcL156W3N/zZrDlKnFBecfWJBu/Zeu2bDoyFOLekcef3mQVQ2h 8KIwa7Hrjco5SY/KJ5b2n7ZJavPfMx6BIHQkhzTlR5pj404ZjpdaGy81dYfuIZBt1DjnRu kOmN+o+JdmXkaoGnL7Go18ioSouaVNZLqc3kfk0z3FL6IUejYZsIEY5GlSmKpvQGkf7e5N ZhLGMPZpw5qVfi5zMw7Yt7IsrPK5yjbg4sUGd0E6KhMP7adAaxg1jNLfsHcQAFhd7LkMVF 9YWg0vrcsQwTaLVWKkZzkbgOXNw/yrMz3UsGzvk9RfaAXYspAJfohwukZYeDHg== Date: Wed, 19 Apr 2023 09:13:26 +0200 From: Luca Ceresoli To: Wolfram Sang , Tomi Valkeinen Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, Rob Herring , Krzysztof Kozlowski , Andy Shevchenko , Matti Vaittinen , Laurent Pinchart , Mauro Carvalho Chehab , Peter Rosin , Liam Girdwood , Mark Brown , Sakari Ailus , Michael Tretter , Hans Verkuil , Mike Pagano , Krzysztof =?UTF-8?Q?Ha=C5=82asa?= , Marek Vasut , Satish Nagireddy , Luca Ceresoli Subject: Re: [PATCH v10 1/8] i2c: add I2C Address Translator (ATR) support Message-ID: <20230419091326.1327018d@booty> In-Reply-To: References: <20230222132907.594690-1-tomi.valkeinen@ideasonboard.com> <20230222132907.594690-2-tomi.valkeinen@ideasonboard.com> Organization: Bootlin X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Wolfram, Tomi, On Tue, 18 Apr 2023 16:25:02 +0200 Wolfram Sang wrote: > Hi Tomi, hi Luca, > > as mentioned on IRC already, good move to use bus notifiers here and > drop the generic attach/detach callbacks. Those were a show stopper for > me. This version is nicely self contained. I like that! > > > diff --git a/Documentation/i2c/index.rst b/Documentation/i2c/index.rst > > index 6270f1fd7d4e..aaf33d1315f4 100644 > > --- a/Documentation/i2c/index.rst > > +++ b/Documentation/i2c/index.rst > > @@ -16,6 +16,7 @@ Introduction > > instantiating-devices > > busses/index > > i2c-topology > > + muxes/i2c-atr > > The muxes-dir is only for the description of mux drivers. I'd prefer to > have this document not in the sub-dir. Also, renaming the document to > "address-translations.rst" might be worth discussing. > > > muxes/i2c-mux-gpio > > i2c-sysfs > > > > diff --git a/Documentation/i2c/muxes/i2c-atr.rst b/Documentation/i2c/muxes/i2c-atr.rst > > new file mode 100644 > > index 000000000000..da226fd4de63 > > --- /dev/null > > +++ b/Documentation/i2c/muxes/i2c-atr.rst > > @@ -0,0 +1,97 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +===================== > > +Kernel driver i2c-atr > > Maybe "I2C address translations"? Even better: "I2C address translator dirvers", or just "I2C address translators"? Here we document a facility to implement a driver for an address translator, and discussion on "address translation" in general is just a part of it. Same for the filename. Uh, I guess this was a journey in the realm of nitpicking, sorry... :) > > +Description > > +----------- > > + > > +An I2C Address Translator (ATR) is a device with an I2C slave parent > > +("upstream") port and N I2C master child ("downstream") ports, and > > +forwards transactions from upstream to the appropriate downstream port > > +with a modified slave address. The address used on the parent bus is > > +called the "alias" and is (potentially) different from the physical > > +slave address of the child bus. Address translation is done by the > > +hardware. > > + > > +An ATR looks similar to an i2c-mux except: > > + - the address on the parent and child busses can be different > > + - there is normally no need to select the child port; the alias used on the > > + parent bus implies it > > + > > +The ATR functionality can be provided by a chip with many other > > +features. This file provides a helper to implement an ATR within your > > I'd like to get rid of all "your". Maybe "client driver" here? I agree. > > + > > +I2C ATR functions and data structures > > +------------------------------------- > > + > > ... > > > +/** > > + * struct i2c_atr_cli2alias_pair - Holds the alias assigned to a client. > > I stumbled over this one because "cli" is "command line interface" for > me... The long version isn't much longer: 'i2c_atr_client_alias_pair' > But I'd be also fine with: 'i2c_atr_alias_pair' The short one looks better to me. The only "alias" involved in ATRs is the client alias, thus no ambiguity. Best regards, Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com