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authorDavid Brownell <david-b@pacbell.net>2008-01-27 18:14:46 +0100
committerJean Delvare <khali@hyperion.delvare>2008-01-27 18:14:46 +0100
commitbf3e2d1d9b860591f3f204aa66d6a3c30058818d (patch)
treeaf5683e3ff7ba26913e2f77bc8cf227702049590 /drivers/i2c
parentcf978ab2846d86709802f38c80d1d53da364bf51 (diff)
downloadlinux-bf3e2d1d9b860591f3f204aa66d6a3c30058818d.tar.bz2
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 <dbrownell@users.sourceforge.net> Signed-off-by: Jean Delvare <khali@linux-fr.org>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/algos/i2c-algo-bit.c24
1 files changed, 20 insertions, 4 deletions
diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index 260c5d70b0b4..35812823787b 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;