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 <Enrik.Berkhan@xxxxxx>
> Reviewed-by: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
> ---
> 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 */
> --
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--
Pengutronix e.K. | Wolfram Sang |
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