cvs commit: src/etc Makefile sensorsd.conf src/etc/defaults rc.conf src/etc/rc.d Makefile sensorsd src/lib/libc/gen sysctl.3 src/sbin/sysctl sysctl.8 sysctl.c src/share/man/man5 rc.conf.5 src/share/man/man9 Makefile sensor_attach.9 src/sys/conf files ...

Alexander Leidinger netchild at
Thu Oct 18 01:06:03 PDT 2007

Quoting Bernd Walter <ticso at> (from Wed, 17 Oct 2007  
17:52:25 +0200):

> For example in the embedded world we can have an i2c system with
> commonly used addresses reused for different purpose.

Not talking about the specific part at hand (probing i2c), but  
regarding embedded devices: there you craft your kernel by hand anyway  
after deciding what you need and what not.

> Another example is that there are i2c switches used on alpha systems,
> such as the AS4100 - we never supported i2c on alpha, but this doesn't
> mean that other systems don't use it as well.

Do you know about amd64/i386 systems (where the code you talk about is  
used) where this is the case? If not, do you think that with the  
vendor mentality of saving every fraction of a cent it is likely, that  
they use i2c switches?

> Yet another example are the famous atmel eeprom chips used in some IBM
> notebooks which died on such an access.

That's bad. Can they be affected with by the code in question?

> Then we have a bug on some i2c controllers (namely the twi in Atmel
> ARM9 chips), which makes it impossible to safely get the ack state
> on addressing.

Are you talking about embedded stuff, or about stuff which is used on  

> On Mon, Oct 15, 2007 at 08:15:07AM +0200, Alexander Leidinger wrote:
>> Quoting Poul-Henning Kamp <phk at> (from Sun, 14 Oct 2007
>> 17:54:21 +0000):
>> Could you please explain how you want to integrate devices with
>> newbus, which are only accessible via the i2c bus? Feel free to show
>> us example code for one of those of our drivers which access the i2c
>> bus, which already existed before this commit.
> For example the ds1672 driver (sys/dev/iicbus/ds1672.c) writen by sam:
>     at91_twi0
>       iicbus0
> [...]
>         ds16720 at addr=0xd0
> [...]
> The device name is a bit unfortunate - it consists of ds1672 beeing
> the driver name and 0 beeing the instance, but this is unrelated.
> The DS1672 is used as an RTC for some ARM boards, but it is written
> machine independend.

Thanks for this example. Do you know enough about this code that you  
can help further if Constantine has questions regarding it and Sam has  
no time to answer?


--  Alexander @ PGP ID = B0063FE7     netchild @  : PGP ID = 72077137
Any circuit design must contain at least one part which is obsolete, two parts
which are unobtainable, and three parts which are still under development.

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