Commit 0d840d42 authored by Jacopo Mondi's avatar Jacopo Mondi Committed by Mauro Carvalho Chehab
Browse files

media: i2c: ov5647: Use bus-locked i2c_transfer() 



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 an 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: default avatarJacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: default avatarTommaso Merciai <tomm.merciai@gmail.com>
Reviewed-by: default avatarDave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: default avatarSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@kernel.org>
parent ca4331bd

drivers/media/i2c/ov5647.c

+18 −12
Original line number Diff line number Diff line
@@ -629,23 +629,29 @@ 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);

	if (ret < 0) {

		dev_dbg(&client->dev, "%s: i2c write error, reg: %x\n",

			__func__, reg);

		return ret;

	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 != 2) {

		dev_err(&client->dev, "%s: i2c read error, reg: %x = %d\n",

			__func__, reg, ret);

		return ret >= 0 ? -EINVAL : 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;

}