Hi, On Mon, Oct 27, 2014 at 11:46:01AM -0700, Martin Belanger wrote: > This is regarding a series of emails between Guenter Roeck and Jean > Delvare titled "Problem with multiple i2c multiplexers on one bus, and > mux bus naming" sent in November 2013. Ref: > http://thread.gmane.org/gmane.linux.drivers.i2c/16980 Please CC those people then, too. That helps getting their attention. I've done this now. > I'm having the same problem with multiple PCA954x multiplexers on the > same bus and there is no way to tell them apart just by looking at the > "name" file. > > There was a suggestion to change the name from "i2c-N-mux (chan_id M)" > to "i2c-N-mux-XX (chan_id M)" or even "i2c-N-mux-i2c-XX (chan_id M)", > where XX is the multiplexer's i2c address. That would solve my > problem, but unfortunately it looks like Guenter never submitted the > patch (or maybe it was rejected?). It just dropped off :( But you guys have my attention now, let's fix this issue for 3.19! I am just reading through the old mails and will think about it. Input is welcome. > I would like to submit a similar change, but I was thinking of adding > a module parameter so that the change is not the default behavior. > The idea is to preserve backward compatibility for applications that > don't require this fix. For example, modprobe i2c-dev > explicit_mux_id=1 would use i2c-N-mux-i2c-XX (chan_id M), whereas > modprobe i2c-dev would default to the current behavior: i.e. i2c-N-mux > (chan_id M). I don't like the need to set a module parameter to fix a flaw. I do consider changing the ABI to have better strings in "name". But as said, I need to think about it a little more... Thanks, Wolfram
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