Hi Jean, can you pick this one up? I think it qualifies as a bugfix.
Regards, Wolfram On Wed, Apr 15, 2009 at 09:45:00AM +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 PCA9564 data sheet (2006-09-01) and the same > is done for other NACK states as well. > > Further, state 0x38 isn't handled completely, either. Try to do another > START in this case like the data sheet says. As this couldn't be tested, > I've added a comment to try to reset the chip if the START doesn't help > as suggested by Wolfram Sang. > > Signed-off-by: Enrik Berkhan <[email protected]> > Reviewed-by: Wolfram Sang <[email protected]> > --- > drivers/i2c/algos/i2c-algo-pca.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > Index: drivers/i2c/algos/i2c-algo-pca.c > =================================================================== > --- drivers/i2c/algos/i2c-algo-pca.c.orig 2008-12-25 00:26:37.000000000 > +0100 > +++ drivers/i2c/algos/i2c-algo-pca.c 2009-04-15 09:37:22.000000000 +0200 > @@ -270,10 +270,21 @@ 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); > goto out; > > case 0x38: /* Arbitration lost during SLA+W, SLA+R or data > bytes */ > DEB2("Arbitration lost\n"); > + /* > + * The PCA9564 data sheet (2006-09-01) says "A > + * START condition will be transmitted when the > + * bus becomes free (STOP or SCL and SDA high)" > + * when the STA bit is set (p. 11). > + * > + * In case this won't work, try pca_reset() > + * instead. > + */ > + pca_start(adap); > goto out; > > case 0x58: /* Data byte has been received; NOT ACK has been > returned */ > -- > 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 -- Pengutronix e.K. | Wolfram Sang | Industrial Linux Solutions | http://www.pengutronix.de/ |
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