Hi Wolfram,
On Tue, Apr 07, 2009 at 11:04:09PM +0200, Wolfram Sang wrote:
> On Tue, Apr 07, 2009 at 12:38:56PM +0200, Enrik Berkhan wrote:
> > Currently, the i2c-algo-pca driver does nothing if the chip enters state
> > 0x30 (Data byte in I2CDAT has been transmitted; NOT ACK has been
> > received). Thus, the i2c bus connected to the controller gets stuck
> > afterwards.
> >
> > I have seen this kind of error on a custom board in certain load
> > situations most probably caused by interference or noise.
> >
> > A possible reaction is to let the controller generate a STOP condition.
> > This is documented in the controller data sheet and the same is done for
> > other NACK states as well.
> >
> > Signed-off-by: Enrik Berkhan <Enrik.Berkhan@xxxxxx>
> > ---
> > drivers/i2c/algos/i2c-algo-pca.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > Index: drivers/i2c/algos/i2c-algo-pca.c
> > ===================================================================
> > --- drivers/i2c/algos/i2c-algo-pca.c.orig 2009-04-07 11:23:08.000000000 +0200
> > +++ drivers/i2c/algos/i2c-algo-pca.c 2009-04-07 11:24:56.000000000 +0200
> > @@ -270,10 +270,12 @@ static int pca_xfer(struct i2c_adapter *
> >
> > case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
> > DEB2("NOT ACK received after data byte\n");
> > + pca_stop(adap);
>
> This looks okay.
>
> > goto out;
> >
> > case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
> > DEB2("Arbitration lost\n");
> > + // XXX pca_start()? pca_reset()?
>
> (No // comments, see CodingStyle)
Yes, of course. Read that as "RFC" :)
> I think we should do something here, too. The manual says something about doing
> another start. What about doing this and adding a comment that possibly a reset
> is another thing to try in case of problems?
That sounds good. Updated version will follow.
Enrik
--
Enrik Berkhan
Electronics Design Engineer
GE Oil & Gas
PII Pipeline Solutions
T +49 7244 732 476
F +49 7244 732 304
E enrik.berkhan@xxxxxx
PII Pipetronix GmbH, Lorenzstraße 10, 76297 Stutensee, Deutschland
Geschäftsführer: David Allen, Werner van Wickeren
Sitz der Gesellschaft: Stutensee
Amtsgericht Mannheim HRB 702297
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Deutsche Bank Karlsruhe, BLZ 660 700 04, Kto: 1 435 700 00
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