From bf3e2d1d9b860591f3f204aa66d6a3c30058818d Mon Sep 17 00:00:00 2001 From: David Brownell Date: Sun, 27 Jan 2008 18:14:46 +0100 Subject: [PATCH] i2c-algo-bit: Fix NAK/ARB comments Update comments and logging on return path for byte writes. NAK is an error, to be reported or optionally ignored. Timeouts are always errors. Lost arbitration is not currently handled, so don't even list it as an option in the error message. Don't return bogus EFAULT code for inappropriate NAK; EIO is better, there is no bad userspace address in question. Signed-off-by: David Brownell Signed-off-by: Jean Delvare --- drivers/i2c/algos/i2c-algo-bit.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c index 260c5d70b0b..35812823787 100644 --- a/drivers/i2c/algos/i2c-algo-bit.c +++ b/drivers/i2c/algos/i2c-algo-bit.c @@ -357,10 +357,26 @@ static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) count--; temp++; wrcount++; - } else { /* arbitration or no acknowledge */ - dev_err(&i2c_adap->dev, "sendbytes: error - bailout.\n"); - return (retval<0)? retval : -EFAULT; - /* got a better one ?? */ + + /* A slave NAKing the master means the slave didn't like + * something about the data it saw. For example, maybe + * the SMBus PEC was wrong. + */ + } else if (retval == 0) { + dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n"); + return -EIO; + + /* Timeout; or (someday) lost arbitration + * + * FIXME Lost ARB implies retrying the transaction from + * the first message, after the "winning" master issues + * its STOP. As a rule, upper layer code has no reason + * to know or care about this ... it is *NOT* an error. + */ + } else { + dev_err(&i2c_adap->dev, "sendbytes: error %d\n", + retval); + return retval; } } return wrcount; -- 2.41.1