[PATCH 2/2] media: i2c: ov5647: Use bus-locked i2c_transfer()

[Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>]

The ov5647_read() functions calls i2c_master_send() and
i2c_master_read() in sequence. However this leaves space for other
clients to contend the bus and insert a unrelated transaction in between
the two calls.

Replace the two calls with a single i2c_transfer() one, that locks the
bus in between the transactions.

Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
---
 drivers/media/i2c/ov5647.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
index 0b88ac6dee41..a423ee8fe20c 100644
--- a/drivers/media/i2c/ov5647.c
+++ b/drivers/media/i2c/ov5647.c
@@ -631,23 +631,29 @@ static int ov5647_write(struct v4l2_subdev *sd, u16 reg, u8 val)

 static int ov5647_read(struct v4l2_subdev *sd, u16 reg, u8 *val)
 {
-	unsigned char data_w[2] = { reg >> 8, reg & 0xff };
 	struct i2c_client *client = v4l2_get_subdevdata(sd);
+	u8 buf[2] = { reg >> 8, reg & 0xff };
+	struct i2c_msg msg[2];
 	int ret;

-	ret = i2c_master_send(client, data_w, 2);
+	msg[0].addr = client->addr;
+	msg[0].flags = client->flags;
+	msg[0].buf = buf;
+	msg[0].len = sizeof(buf);
+
+	msg[1].addr = client->addr;
+	msg[1].flags = client->flags | I2C_M_RD;
+	msg[1].buf = buf;
+	msg[1].len = 1;
+
+	ret = i2c_transfer(client->adapter, msg, 2);
 	if (ret < 0) {
-		dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n",
+		dev_err(&client->dev, "%s: i2c read error, reg: %x\n",
 			__func__, reg);
 		return ret;
 	}

-	ret = i2c_master_recv(client, val, 1);
-	if (ret < 0) {
-		dev_dbg(&client->dev, "%s: i2c read error, reg: %x\n",
-				__func__, reg);
-		return ret;
-	}
+	*val = buf[0];

 	return 0;
 }
--
2.39.0