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 X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1BBCC282DD for ; Wed, 8 Jan 2020 13:27:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7DA492067D for ; Wed, 8 Jan 2020 13:27:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728185AbgAHN1M (ORCPT ); Wed, 8 Jan 2020 08:27:12 -0500 Received: from sauhun.de ([88.99.104.3]:35074 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726087AbgAHN1K (ORCPT ); Wed, 8 Jan 2020 08:27:10 -0500 Received: from localhost (p54B332C6.dip0.t-ipconnect.de [84.179.50.198]) by pokefinder.org (Postfix) with ESMTPSA id D6CE02C05CE; Wed, 8 Jan 2020 14:27:08 +0100 (CET) Date: Wed, 8 Jan 2020 14:27:08 +0100 From: Wolfram Sang To: Laurent Pinchart Cc: Luca Ceresoli , Wolfram Sang , linux-i2c@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Kieran Bingham , Jacopo Mondi , Vladimir Zapolskiy Subject: Re: [RFC PATCH 3/5] i2c: core: add function to request an alias Message-ID: <20200108132708.GC834@kunai> References: <20191231161400.1688-1-wsa+renesas@sang-engineering.com> <20191231161400.1688-4-wsa+renesas@sang-engineering.com> <20200101165515.GC6226@pendragon.ideasonboard.com> <20200102211327.GB1030@kunai> <20200103001056.GJ4843@pendragon.ideasonboard.com> <20200107171357.GO4871@pendragon.ideasonboard.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="gr/z0/N6AeWAPJVB" Content-Disposition: inline In-Reply-To: <20200107171357.GO4871@pendragon.ideasonboard.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org --gr/z0/N6AeWAPJVB Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > > It would be nice, but I'm not sure this is really doable. Say the DT for > > board X lists all the used slave addresses. Then the kernel would assume > > all the other addresses are available. But then somebody includes the DT > > of board X in the DT for product Z, based on board X + add-on board Y. > > Add-on board Y has 2 I2C chips, but only one is described in DT. Now the > > kernel still thinks it knows all the used address, but this is wrong. >=20 > That's the fault of the system integrator though. We can't prevent > people from making incorrect DT, and we shouldn't go to great length to > still support them. Currently, there is no paradigm that all I2C busses must be fully described. Enforcing it now all of a sudden is not too user-friendly, or? Especially since calling read_byte once is not necessarily "great length" in my book. If you have 8 cameras on a 400kHz bus, the 8 * 18 bits should take 360us if I am not mistaken? --gr/z0/N6AeWAPJVB Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEOZGx6rniZ1Gk92RdFA3kzBSgKbYFAl4V2KwACgkQFA3kzBSg KbYc6A//clREGfV+3ngdxoXUQHbE1cQlQ7+nwFe1i7Iu7YFPVHS5qJ/+YmA8/HPS qNlHZlQJUCUrCuarIpHScSWzlOkJAr76K+u6WT5hVHkzSxP7NLIGRLdM35xwhDxe G0kFrc94Nb0HpaKJfE9l4chECaTl7e0iJ8vV/aSfzS+ftZOTRAIJDxDjDCezjvvC HojYRv58dS/6tySa4le95Zy7bG1VVyAZixmhT6I8IX+wRsr63VAsOQggda+Z73dz MnC2KpBodyIj4e8yYHQbeXCR/VDti1waZvLgJL3htnfGnFuO5syyAUmgRy5hVDcy Vq3apMlUkI6i3NCpYMrww/MZTSlp4jw7lF1W4Y9ZMUFzeWWxfGO9TiFcXxIF5jly skdTI2e3+A+W34mOMLQ28zlZ2C1TRPnI/beZ62bkjDAE/hTSmwSDAvt8+zf17+N1 pV3bimDQLSGKkQIsAwgpCUiLml0ZEioYioMD6L/uSM3DMlBvGi7ySgF97NCzXhqf IWeRjDRO/JDwvgC5JxBjnk3qtD/815g9b2eGtMhtfGqsGm6qIbgEV33ZrjkW0QOp JwpoEWtK/NZJ5N7PAgYPd3Im6DP1NoCh7sNShU4TVaqIcjltac9jDAZ5MtmWCA79 bT6RKumFoNUG9N5gN5W7oXmi06A9ieBab4sipKY7lzhEl/3sAIQ= =L83f -----END PGP SIGNATURE----- --gr/z0/N6AeWAPJVB--