Re: [PATCH v2] iio: imu: st_lsm6dsx: Fix selection of ST_LSM6DS3_ID

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 16 Dec 2019 13:41:20 +0100
Stephan Gerhold <stephan@gerhold.net> wrote:

> At the moment, attempting to probe a device with ST_LSM6DS3_ID
> (e.g. using the st,lsm6ds3 compatible) fails with:
> 
>     st_lsm6dsx_i2c 1-006b: unsupported whoami [69]
> 
> ... even though 0x69 is the whoami listed for ST_LSM6DS3_ID.
> 
> This happens because st_lsm6dsx_check_whoami() also attempts
> to match unspecified (zero-initialized) entries in the "id" array.
> ST_LSM6DS3_ID = 0 will therefore match any entry in
> st_lsm6dsx_sensor_settings (here: the first), because none of them
> actually have all 12 entries listed in the "id" array.
> 
> Avoid this by additionally checking if "name" is set,
> which is only set for valid entries in the "id" array.
> 
> Note: Although the problem was introduced earlier it did not surface until
> commit 52f4b1f19679 ("iio: imu: st_lsm6dsx: add support for accel/gyro unit of lsm9ds1")
> because ST_LSM6DS3_ID was the first entry in st_lsm6dsx_sensor_settings.
> 
> Fixes: d068e4a0f921 ("iio: imu: st_lsm6dsx: add support to multiple devices with the same settings")
> Cc: <stable@vger.kernel.org> # 5.4
> Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Applied to the fixes-togreg branch of iio.git.

Thanks,

Jonathan

> ---
> v1: https://lore.kernel.org/linux-iio/20191209170541.198206-1-stephan@gerhold.net/
> 
> Changes in v2:
>   - Add Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
>   - Add Fixes tag
>   - Cc stable@vger.kernel.org
> ---
>  drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
> index a7d40c02ce6b..b921dd9e108f 100644
> --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
> @@ -1301,7 +1301,8 @@ static int st_lsm6dsx_check_whoami(struct st_lsm6dsx_hw *hw, int id,
>  
>  	for (i = 0; i < ARRAY_SIZE(st_lsm6dsx_sensor_settings); i++) {
>  		for (j = 0; j < ST_LSM6DSX_MAX_ID; j++) {
> -			if (id == st_lsm6dsx_sensor_settings[i].id[j].hw_id)
> +			if (st_lsm6dsx_sensor_settings[i].id[j].name &&
> +			    id == st_lsm6dsx_sensor_settings[i].id[j].hw_id)
>  				break;
>  		}
>  		if (j < ST_LSM6DSX_MAX_ID)