Re: [PATCH v7 1/7] iio: dac: ad5696: properly check i2c_transfer() return value

On Fri, 10 Jul 2026 12:20:45 +0100
Rodrigo Alencar via B4 Relay <[email protected]> wrote:

> From: Rodrigo Alencar <[email protected]>
> 
> Verify that the expected number of i2c messages were transferred when
> ad5686_i2c_read() is called. This issue exists since the support for I2C
> devices where first introduced.
> 
> Fixes: 4177381b4401 ("iio:dac:ad5686: Add AD5671R/75R/94/94R/95R/96/96R support")
> Reported-by: [email protected]
> Closes: https://lore.kernel.org/all/[email protected]/
> Signed-off-by: Rodrigo Alencar <[email protected]>
FWIW, as I understand it, these are vanishingly rare unless the device is
doing something unusual so I'll leave this for merge with the rest of the series. 

Jonathan

> ---
>  drivers/iio/dac/ad5696-i2c.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/dac/ad5696-i2c.c b/drivers/iio/dac/ad5696-i2c.c
> index 279309329b64..6f726e6301a6 100644
> --- a/drivers/iio/dac/ad5696-i2c.c
> +++ b/drivers/iio/dac/ad5696-i2c.c
> @@ -40,8 +40,8 @@ static int ad5686_i2c_read(struct ad5686_state *st, u8 addr)
>  				      0x00);
>  
>  	ret = i2c_transfer(i2c->adapter, msg, 2);
> -	if (ret < 0)
> -		return ret;
> +	if (ret != 2)
> +		return ret < 0 ? ret : -EIO;
>  
>  	return be16_to_cpu(st->data[0].d16);
>  }
>