linux-kernel - Re: [PATCH] Revert "Staging: iio: adt7316: Add an extra check for 'ret' equals to 0"

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Date:   Thu, 06 Dec 2018 01:25:55 +0530
From:   Shreeya Patel <shreeya.patel23498@...il.com>
To:     Jeremy Fertic <jeremyfertic@...il.com>, jic23@...nel.org,
        linux-iio@...r.kernel.org
Cc:     lars@...afoo.de, Michael.Hennerich@...log.com, knaack.h@....de,
        pmeerw@...erw.net, gregkh@...uxfoundation.org,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Revert "Staging: iio: adt7316: Add an extra check for
 'ret' equals to 0"

On Tue, 2018-12-04 at 18:49 -0700, Jeremy Fertic wrote:
> This reverts commit 00426e99789357dbff7e719a092ce36a3ce49d94.
> 
> i2c_smbus_read_byte() returns 0 when a byte with the value 0 is read
> from
> the device. This is a valid read so revert the check for 0.
> 
> Signed-off-by: Jeremy Fertic <jeremyfertic@...il.com>
> ---

Hi Jeremy,

As per my understanding, 0 value indicates no error but no data read.
Then how can this be a valid case?

Can you please make me understand that how can we consider this as a
valid case even when no data has been read?


Thanks

>  drivers/staging/iio/addac/adt7316-i2c.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/staging/iio/addac/adt7316-i2c.c
> b/drivers/staging/iio/addac/adt7316-i2c.c
> index ac91163656b5..2d51bd425662 100644
> --- a/drivers/staging/iio/addac/adt7316-i2c.c
> +++ b/drivers/staging/iio/addac/adt7316-i2c.c
> @@ -30,10 +30,6 @@ static int adt7316_i2c_read(void *client, u8 reg,
> u8 *data)
>  	}
>  
>  	ret = i2c_smbus_read_byte(client);
> -
> -	if (!ret)
> -		return -EIO;
> -
>  	if (ret < 0) {
>  		dev_err(&cl->dev, "I2C read error\n");
>  		return ret;