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 <[email protected]> > > --- > > 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 [email protected] PII Pipetronix GmbH, Lorenzstraße 10, 76297 Stutensee, Deutschland Geschäftsführer: David Allen, Werner van Wickeren Sitz der Gesellschaft: Stutensee Amtsgericht Mannheim HRB 702297 USt-ID: DE 244323981, Steuer-Nr.: 5930/0173 Deutsche Bank Karlsruhe, BLZ 660 700 04, Kto: 1 435 700 00 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
