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    SubjectRe: i2c_adapter i2c-0: Bus collision!

    about a year ago I asked for help with my motherboard, claiming i2c bus
    collisions all the time. Now I found the solution, the sensor uses the
    isa bus, not the i2c. Funny it sometimes worked with i2c-viapro, but
    with i2c-isa it works all the time :)

    Sorry for not finding that out earlier.

    Best regards,

    lør, 17,.01.2004 kl. 09.48 +0100, skrev Jean Delvare:
    > > sorry to bother you again, but this didn't tell you anything about
    > > what's going on?
    > Sorry for the delay. Too much work, not enough time. You know the story
    > I guess.
    > > > I forgot to mention it in my last mail, but I sometime has to
    > > > reload the modules before "sensors" finds any sensor.
    > As we load sensor chip drivers, we make sure that the chip we want to
    > handle is what we think it is. Technically, this means reading from a
    > few registers and compare the values with what we would expect for this
    > chip. So the same read errors that make your hardware monitoring values
    > jump make the chip identification fail sometimes.
    > > > Attached three runs. Seems to be some read errors :( On these three
    > > > runs I got first three bus-collisions, then one, and last two.
    > Not all read errors are detected as bus collisions. Anyway, you got
    > loads of 'XX' as I expected, "moving" from run to run, which means that
    > your i2c bus is unreliable.
    > My conclusion would be: bad hardware design generates noise on the i2c
    > bus, resulting in read errors.
    > > > > Did you have to enable any particular option in MBM?
    > > >
    > > > Nah, it just worked :)

    > I asked Alex van Kaam (MBM's brilliant author) about his strategy with
    > bus collisions. To make it short, he explained he resets the bus on
    > problems. If you confirm that the smbus MBM detected was Via, Alex will
    > send me his code so that I can compare with ours, just in case. But I
    > doubt it'll change anything (our driver is working, it's just a matter
    > of how errors are - or aren't - handled).
    > Basically we don't handle read errors at all (because it is so rare).
    > Handling them correctly would make all chip drivers (and possibly i2c
    > core and bus drivers as well) more complex. I'm not sure it's worth it.
    > That said, a similar problem was reported with W83L785TS-S chips (A7N8X
    > motherboards). I think that the cause is different (BIOS trying to
    > access the bus at the same time we do) but the consequences are the
    > same. I plan to add basic error handling to this specific chip driver
    > (don't know when I'll find the time to do so though). If it works and
    > could be extended to other drivers as well, we'll consider it.
    > > > I guess this is unsolvable, but I just wanted to hear what you say.
    > > > Kinda weird it works so well with MBM, but that's ok. It's just for
    > > > fun I want it to work.
    > I think it is work-around-able, but doubt it's worth it. Anyway, thanks
    > for reporting, as it increased our knowledge of the topic.
    > > > Thanks for your reply :)
    > You're welcome. Sorry for the delay again.

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