platform/chrome: correct cros_ec_prepare_tx() usage

cros_ec_prepare_tx() returns either:
- >= 0 for number of prepared bytes.
- < 0 for -errno.

Correct the comment and make sure all callers check the return code.

Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20220513044143.1045728-3-tzungbi@kernel.org

6 files changed, 14 insertions, 2 deletions

diff --git a/drivers/platform/chrome/cros_ec_i2c.c b/drivers/platform/chrome/cros_ec_i2c.c
index 22feb0fd4ce7..a4f305f1eb0e 100644
--- a/drivers/platform/chrome/cros_ec_i2c.c
+++ b/drivers/platform/chrome/cros_ec_i2c.c
@@ -89,6 +89,8 @@ static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,
 
 	ec_dev->dout++;
 	ret = cros_ec_prepare_tx(ec_dev, msg);
+	if (ret < 0)
+		goto done;
 	ec_dev->dout--;
 
 	/* send command to EC and read answer */
diff --git a/drivers/platform/chrome/cros_ec_ishtp.c b/drivers/platform/chrome/cros_ec_ishtp.c
index 4020b8354bae..cb2031cf7106 100644
--- a/drivers/platform/chrome/cros_ec_ishtp.c
+++ b/drivers/platform/chrome/cros_ec_ishtp.c
@@ -521,7 +521,9 @@ static int cros_ec_pkt_xfer_ish(struct cros_ec_device *ec_dev,
 	out_msg->hdr.status = 0;
 
 	ec_dev->dout += OUT_MSG_EC_REQUEST_PREAMBLE;
-	cros_ec_prepare_tx(ec_dev, msg);
+	rv = cros_ec_prepare_tx(ec_dev, msg);
+	if (rv < 0)
+		goto end_error;
 	ec_dev->dout -= OUT_MSG_EC_REQUEST_PREAMBLE;
 
 	dev_dbg(dev,
diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
index 8eeef85a96b1..7677ab3c0ead 100644
--- a/drivers/platform/chrome/cros_ec_lpc.c
+++ b/drivers/platform/chrome/cros_ec_lpc.c
@@ -147,6 +147,8 @@ static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
 	u8 *dout;
 
 	ret = cros_ec_prepare_tx(ec, msg);
+	if (ret < 0)
+		goto done;
 
 	/* Write buffer */
 	cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
index db1c8ba43171..2d6d3fbfa905 100644
--- a/drivers/platform/chrome/cros_ec_proto.c
+++ b/drivers/platform/chrome/cros_ec_proto.c
@@ -164,7 +164,7 @@ static int send_command(struct cros_ec_device *ec_dev,
  * only SPI uses it. Once LPC uses the same protocol it can start using it.
  * I2C could use it now, with a refactor of the existing code.
  *
- * Return: 0 on success or negative error code.
+ * Return: number of prepared bytes on success or negative error code.
  */
 int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
 		       struct cros_ec_command *msg)
diff --git a/drivers/platform/chrome/cros_ec_rpmsg.c b/drivers/platform/chrome/cros_ec_rpmsg.c
index d96d15b8ca94..39d3b50a7c09 100644
--- a/drivers/platform/chrome/cros_ec_rpmsg.c
+++ b/drivers/platform/chrome/cros_ec_rpmsg.c
@@ -89,6 +89,8 @@ static int cros_ec_pkt_xfer_rpmsg(struct cros_ec_device *ec_dev,
 
 	ec_msg->result = 0;
 	len = cros_ec_prepare_tx(ec_dev, ec_msg);
+	if (len < 0)
+		return len;
 	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
 
 	reinit_completion(&ec_rpmsg->xfer_ack);
diff --git a/drivers/platform/chrome/cros_ec_spi.c b/drivers/platform/chrome/cros_ec_spi.c
index 8493af0f680e..589f18e9537d 100644
--- a/drivers/platform/chrome/cros_ec_spi.c
+++ b/drivers/platform/chrome/cros_ec_spi.c
@@ -401,6 +401,8 @@ static int do_cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev,
 	unsigned long delay;
 
 	len = cros_ec_prepare_tx(ec_dev, ec_msg);
+	if (len < 0)
+		return len;
 	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
 
 	/* If it's too soon to do another transaction, wait */
@@ -544,6 +546,8 @@ static int do_cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
 	unsigned long delay;
 
 	len = cros_ec_prepare_tx(ec_dev, ec_msg);
+	if (len < 0)
+		return len;
 	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
 
 	/* If it's too soon to do another transaction, wait */