linux-kernel - [PATCH 2/3] i2c: xlp9xx: Handle NACK on DATA properly

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Message-Id: <1519737980-27997-2-git-send-email-george.cherian@cavium.com>
Date:   Tue, 27 Feb 2018 13:26:19 +0000
From:   George Cherian <george.cherian@...ium.com>
To:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     wsa@...-dreams.de, George Cherian <george.cherian@...ium.com>
Subject: [PATCH 2/3] i2c: xlp9xx: Handle NACK on DATA properly

In case we receive NACK on DATA we shouldn't be resetting the controller,
rather we should issue STOP command. This will terminate the current
transaction and -EIO is returned.

While at that handle the SMBus Quick Command properly.
We shouldn't be setting the XLP9XX_I2C_CMD_READ/WRITE for such
transactions.

Signed-off-by: George Cherian <george.cherian@...ium.com>
---
 drivers/i2c/busses/i2c-xlp9xx.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-xlp9xx.c b/drivers/i2c/busses/i2c-xlp9xx.c
index 42dd1fa..eb8913e 100644
--- a/drivers/i2c/busses/i2c-xlp9xx.c
+++ b/drivers/i2c/busses/i2c-xlp9xx.c
@@ -352,7 +352,9 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg,
 
 	/* set cmd reg */
 	cmd = XLP9XX_I2C_CMD_START;
-	cmd |= (priv->msg_read ? XLP9XX_I2C_CMD_READ : XLP9XX_I2C_CMD_WRITE);
+	if (msg->len)
+		cmd |= (priv->msg_read ?
+			XLP9XX_I2C_CMD_READ : XLP9XX_I2C_CMD_WRITE);
 	if (last_msg)
 		cmd |= XLP9XX_I2C_CMD_STOP;
 
@@ -361,12 +363,12 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg,
 	timeleft = msecs_to_jiffies(XLP9XX_I2C_TIMEOUT_MS);
 	timeleft = wait_for_completion_timeout(&priv->msg_complete, timeleft);
 
-	if (priv->msg_err) {
+	if (priv->msg_err & XLP9XX_I2C_INTEN_BUSERR) {
 		dev_dbg(priv->dev, "transfer error %x!\n", priv->msg_err);
-		if (priv->msg_err & XLP9XX_I2C_INTEN_BUSERR)
-			xlp9xx_i2c_init(priv);
-		return (priv->msg_err & XLP9XX_I2C_INTEN_NACKADDR) ?
-			-ENXIO : -EIO;
+		xlp9xx_write_i2c_reg(priv, XLP9XX_I2C_CMD, XLP9XX_I2C_CMD_STOP);
+		return -EIO;
+	} else if (priv->msg_err & XLP9XX_I2C_INTEN_NACKADDR) {
+		return -ENXIO;
 	}
 
 	if (timeleft == 0) {
-- 
2.1.4