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); goto out; case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */ DEB2("Arbitration lost\n"); + // XXX pca_start()? pca_reset()? 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
