Re: [PATCH] media: staging: atomisp: improve error handling in gc2235_detect()

From: Sakari Ailus
Date: Mon May 24 2021 - 11:36:29 EST


Hi Tom,

On Fri, May 21, 2021 at 12:48:05PM -0700, trix@xxxxxxxxxx wrote:
> From: Tom Rix <trix@xxxxxxxxxx>
>
> Static analysis reports this representative problem
>
> atomisp-gc2235.c:867:20: warning: The right operand
> of '|' is a garbage value
> id = ((high << 8) | low);
> ^ ~~~
> When gc2235_read_reg() fails, its return val is never written.
>
> For gc2235_detect(), high and low are or-ed and compared
> with GC2235_ID, 0x2235. Initialize both to 0 and skip
> checking the read returns, it's errors are not passed up, only
> -ENODEV is.
>
> Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
> ---
> drivers/staging/media/atomisp/i2c/atomisp-gc2235.c | 13 +++----------
> 1 file changed, 3 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/staging/media/atomisp/i2c/atomisp-gc2235.c b/drivers/staging/media/atomisp/i2c/atomisp-gc2235.c
> index 38defa0f81513..3b6e02b1f45d1 100644
> --- a/drivers/staging/media/atomisp/i2c/atomisp-gc2235.c
> +++ b/drivers/staging/media/atomisp/i2c/atomisp-gc2235.c
> @@ -849,21 +849,14 @@ static int gc2235_get_fmt(struct v4l2_subdev *sd,
> static int gc2235_detect(struct i2c_client *client)
> {
> struct i2c_adapter *adapter = client->adapter;
> - u16 high, low;
> - int ret;
> + u16 high = 0, low = 0;
> u16 id;
>
> if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
> return -ENODEV;
>
> - ret = gc2235_read_reg(client, GC2235_8BIT,
> - GC2235_SENSOR_ID_H, &high);
> - if (ret) {
> - dev_err(&client->dev, "sensor_id_high = 0x%x\n", high);
> - return -ENODEV;

It'd be nice if the function returned a different value for different
errors, such as there was an I/O error and that the ID was wrong.

> - }
> - ret = gc2235_read_reg(client, GC2235_8BIT,
> - GC2235_SENSOR_ID_L, &low);
> + gc2235_read_reg(client, GC2235_8BIT, GC2235_SENSOR_ID_H, &high);
> + gc2235_read_reg(client, GC2235_8BIT, GC2235_SENSOR_ID_L, &low);
> id = ((high << 8) | low);
>
> if (id != GC2235_ID) {

--
Sakari Ailus