From: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
To: Bob Feretich <bob.feretich-8wbKi1faPaosQv5ZqcSHkQ@public.gmane.org>
Cc: "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
Subject: Re: Another problem with I2C multiplexer bus naming
Date: Sat, 14 Mar 2015 12:00:28 +0100 [thread overview]
Message-ID: <20150314110028.GB970@katana> (raw)
In-Reply-To: <5501E52D.9060400-8wbKi1faPaosQv5ZqcSHkQ@public.gmane.org>
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> >Yes, one can't mix i2c_add_numbered_adapter and i2c_add_adapter well,
> >and this is even documented. However, since you are DT only, this
> >doesn't apply.
> >
> I have not seen any documentation to regarding this topic.
man i2c_add_numbered_adapter
...
* If no devices have pre-been declared for this bus, then be sure to
* register the adapter before any dynamically allocated ones. Otherwise
* the required bus ID may not be available.
...
I was just referring to it to express that this is known behaviour and
not a bug like I first assumed.
> I remember adding an i2c multiplexer to an early beagleboard system years
> ago. I think we were lucky that the fixed i2c bus addresses were probed
> first, so they were not stolen by the multiplexer's dynamic allocations.
You "need" a deferred probe for this clash to happen.
> It would be useful also state that the i2c bus naming mechanism uses aliases
> to name i2c buses.
Care to send a patch? :)
And are you interested in testing the bugfix patches I sent around? I
tested them locally, but verification from the bug-reporter is always
good.
Thanks,
Wolfram
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next prev parent reply other threads:[~2015-03-14 11:00 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-12 4:11 Another problem with I2C multiplexer bus naming Bob Feretich
[not found] ` <1426133507.16219.YahooMailNeo-XYahOdtEMNm2Y7dhQGSVAJOW+3bF1jUfVpNB7YpNyf8@public.gmane.org>
2015-03-12 4:55 ` Another problem with I2C multiplexer bus naming - solved Bob Feretich
[not found] ` <1426136151.37151.YahooMailNeo-XYahOdtEMNlRBbKmAC7my5OW+3bF1jUfVpNB7YpNyf8@public.gmane.org>
2015-03-12 9:44 ` Wolfram Sang
2015-03-12 18:49 ` Bob Feretich
[not found] ` <5501DFCC.6010408-8wbKi1faPaosQv5ZqcSHkQ@public.gmane.org>
2015-03-14 10:49 ` Wolfram Sang
2015-03-12 9:29 ` Another problem with I2C multiplexer bus naming Danielle Costantino
2015-03-12 9:42 ` Wolfram Sang
2015-03-12 11:29 ` Wolfram Sang
2015-03-12 19:12 ` Bob Feretich
[not found] ` <5501E52D.9060400-8wbKi1faPaosQv5ZqcSHkQ@public.gmane.org>
2015-03-14 11:00 ` Wolfram Sang [this message]
2015-05-08 4:57 ` [PATCH 1/1] i2c: documentation of how to set child bus numbers from the device tree Bob Feretich
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