From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: Another problem with I2C multiplexer bus naming - solved Date: Sat, 14 Mar 2015 11:49:39 +0100 Message-ID: <20150314104938.GA970@katana> References: <1426133507.16219.YahooMailNeo@web181502.mail.ne1.yahoo.com> <1426136151.37151.YahooMailNeo@web181506.mail.ne1.yahoo.com> <20150312094423.GB4225@katana> <5501DFCC.6010408@rafresearch.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="ZGiS0Q5IWpPtfppv" Return-path: Content-Disposition: inline In-Reply-To: <5501DFCC.6010408-8wbKi1faPaosQv5ZqcSHkQ@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Bob Feretich Cc: "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Guenter Roeck List-Id: linux-i2c@vger.kernel.org --ZGiS0Q5IWpPtfppv Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Mar 12, 2015 at 11:49:48AM -0700, Bob Feretich wrote: > On 3/12/2015 2:44 AM, Wolfram Sang wrote: > >On Wed, Mar 11, 2015 at 09:55:51PM -0700, Bob Feretich wrote: > > > >>I tried some random things and setting aliases in the dtsi file solved > >>the problem. > > > >Good. > > > >>The use of an alias to set the name of an i2c bus should > >>be documented somewhere! > > > >Well, send a patch adding some documentation where you would have liked > >to see it. > > > >Thanks, > > > > Wolfram > > > The first two places I looked for information were: > * > https://www.kernel.org/doc/Documentation/devicetree/bindings/i2c/i2c-mux.= txt >=20 > This is where I found the info on specifying the multiplexer without > aliases. It would seem logical to add the description of "how to > explicitly name child buses" here. Please do. You know best what kind of information you'd like to see there. > * https://www.kernel.org/doc/Documentation/i2c/muxes/i2c-mux-gpio > Even though this file is for gpio controlled multiplexers, it seemed > like a good spot to look for information on how to specify i2c > multiplexers in general. It only describes the board.c method of > registering adapters. (I don't know which gpio_i2cmux_platform_data > fields would be the equivalent of specifying the device tree aliases.) > Perhaps a cross-reference to the above documentation is appropriate, > since use of customized board.c files is being discouraged. Send a patch and we will see :) > Note that once device trees become dynamic and support hot plugging, the > alias bus naming solution becomes ineffective, unless there is a way to > specify a hierarchical alias that references the bus/adapter id of the > multiplexer. I2C was never considered hot-pluggable in the days. So, anyone wanting to use it this way needs to spend some effort adding it. Some steps have already been taken, though (e.g. dynamic of reconfig). --ZGiS0Q5IWpPtfppv Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVBBJCAAoJEBQN5MwUoCm2L+YQAJx3LLYbIX+18rpTthv2QCQc lCq3W9MC0SEhph+ThQ1r1YCWpdh9qcUaz/Gj/FtBEEQf5mSWukbJWhf5kBlYaHR2 0kmWm1hYD9ps5OGzGjG6MUfYQIzDPRI2evEIBkWPKJvV7keNrgrzcOIjJFaF0spl X2rjxFMBwIiq0viH0S102TpDvrX74T4mFvh+UyXWacFV27m4DwrqKked4Cp81IpP o7hy4QEvsQMYE4sCgTvdZdSZBp/Uq4QnjdcKpO8H5uTy6TtRlC4wDbE5U9+frv7M 0saRSuoYfa34Qfpeic0kRvioaGe/4LDuGAqBWUBMBn5+zLRspEx0B/GJZIwt/F6E xRNmFdimX3fIDXTFtPmB6uYbUhOxmETQgduVZXQM7icCJRK07WmZXgBwTWzxibdg Ih2rA62eRBkT3wePBmcYmkCUGaIzsTO/7rgZyI6BUH2OAmKNuqDdY8Y2ZIO6zyem amOBa0UWajl6jV1D56UtqJk/LhQ2uttDAmw4rGjMLD6vVFRlQ9Jm8uISKMFHlva4 xnupIrcta7xPOE396idfpETT0vz9ns0MwbBy4A7dITNf4mxvmrw4dLJYIhUAmVvH CE6wChJCYSm6AInQDTC5KKT3ZQMoRPn4h+yInwHt5saAHTTeKWbgKpzVtZvyRw8a 2ByJfbzRXH6mbbSSbnSB =JnB1 -----END PGP SIGNATURE----- --ZGiS0Q5IWpPtfppv--