media: ov5647: Fix return codes from ov5647_write/ov5647_read functions.

Previously they were returning positive non-zero codes for success,
which were getting passed up the call stack. Since release 4.19,
do_dentry_open (fs/open.c) has been catching these and flagging an
error. (So this driver has been broken since that date.)

Fixes: 3c2472a [media] media: i2c: Add support for OV5647 sensor
Signed-off-by: David Plowman <david.plowman@raspberrypi.org>
Signed-off-by: Naushir Patuck <naush@raspberrypi.com>

diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
index 0755037..6ecc018 100644 (file)
--- a/drivers/media/i2c/ov5647.c
+++ b/drivers/media/i2c/ov5647.c
@@ -214,9 +214,18 @@ static int ov5647_write(struct v4l2_subdev *sd, u16 reg, u8 val)
        struct i2c_client *client = v4l2_get_subdevdata(sd);
 
        ret = i2c_master_send(client, data, 3);
-       if (ret < 0)
+       /*
+        * Writing the wrong number of bytes also needs to be flagged as an
+        * error. Success needs to produce a 0 return code.
+        */
+       if (ret == 3) {
+               ret = 0;
+       } else {
                dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n",
                                __func__, reg);
+               if (ret >= 0)
+                       ret = -EINVAL;
+       }
 
        return ret;
 }
@@ -228,16 +237,31 @@ static int ov5647_read(struct v4l2_subdev *sd, u16 reg, u8 *val)
        struct i2c_client *client = v4l2_get_subdevdata(sd);
 
        ret = i2c_master_send(client, data_w, 2);
-       if (ret < 0) {
+       /*
+        * A negative return code, or sending the wrong number of bytes, both
+        * count as an error.
+        */
+       if (ret != 2) {
                dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n",
                        __func__, reg);
+               if (ret >= 0)
+                       ret = -EINVAL;
                return ret;
        }
 
        ret = i2c_master_recv(client, val, 1);
-       if (ret < 0)
+       /*
+        * The only return value indicating success is 1. Anything else, even
+        * a non-negative value, indicates something went wrong.
+        */
+       if (ret == 1) {
+               ret = 0;
+       } else {
                dev_dbg(&client->dev, "%s: i2c read error, reg: %x\n",
                                __func__, reg);
+               if (ret >= 0)
+                       ret = -EINVAL;
+       }
 
        return ret;
 }