Re: [PATCH v3 11/24] tvp5150: make read operations atomic

["Frank Schäfer" <fschaefer.oss@googlemail.com>]

Am 28.12.2013 13:16, schrieb Mauro Carvalho Chehab:
> From: Mauro Carvalho Chehab <m.chehab@samsung.com>
>
> Instead of using two I2C operations between write and read,
> use just one i2c_transfer. That allows I2C mutexes to not
> let any other I2C transfer between the two.
>
> Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
> ---
>  drivers/media/i2c/tvp5150.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/media/i2c/tvp5150.c b/drivers/media/i2c/tvp5150.c
> index 89c0b13463b7..d6ba457fcf67 100644
> --- a/drivers/media/i2c/tvp5150.c
> +++ b/drivers/media/i2c/tvp5150.c
> @@ -58,21 +58,19 @@ static int tvp5150_read(struct v4l2_subdev *sd, unsigned char addr)
>  	struct i2c_client *c = v4l2_get_subdevdata(sd);
>  	unsigned char buffer[1];
>  	int rc;
> +	struct i2c_msg msg[] = {
> +		{ .addr = c->addr, .flags = 0,
> +		  .buf = &addr, .len = 1 },
I would use        .buf = buffer        here, too.

> +		{ .addr = c->addr, .flags = I2C_M_RD,
> +		  .buf = buffer, .len = 1 }
> +	};
>  
>  	buffer[0] = addr;
>  
> -	rc = i2c_master_send(c, buffer, 1);
> -	if (rc < 0) {
> -		v4l2_err(sd, "i2c i/o error: rc == %d (should be 1)\n", rc);
> -		return rc;
> -	}
> -
> -	msleep(10);
That's the critical change.

> -
> -	rc = i2c_master_recv(c, buffer, 1);
> -	if (rc < 0) {
> -		v4l2_err(sd, "i2c i/o error: rc == %d (should be 1)\n", rc);
> -		return rc;
> +	rc = i2c_transfer(c->adapter, msg, 2);
> +	if (rc < 0 || rc != 2) {
> +		v4l2_err(sd, "i2c i/o error: rc == %d (should be 2)\n", rc);
> +		return rc < 0 ? rc : -EIO;
>  	}
>  
>  	v4l2_dbg(2, debug, sd, "tvp5150: read 0x%02x = 0x%02x\n", addr, buffer[0]);
Looks good and works without problems with my HVR-900 and WinTV 2
devices (both em28xx).