Re: [PATCH] iio: temperature: tmp117: fix calibbias cache update on I2C write failure

[Joshua Crofts]

On Sat, 22 Aug 2026 01:49:28 +0100
Salah Triki <salah.triki@xxxxxxxxx> wrote:

> The calibbias cache (data->calibbias) was updated before the I2C
> write to TMP117_REG_TEMP_OFFSET was known to succeed. If the write
> failed, the function correctly returned an error, but the driver's
> internal cache had already been updated to the new value.
> 
> This causes the cache and the actual hardware register to go out of
> sync: a subsequent write of the same value would be silently
> skipped by the early "if (off == data->calibbias) return 0;" check,
> since the cache matches even though the register was never
> successfully updated.
> 
> Update data->calibbias only after confirming the I2C write
> succeeded, so the cache always reflects the actual state of the
> device.
> 
> Fixes: df041e737a38 ("iio: temperature: add driver support for ti tmp117")
> Signed-off-by: Salah Triki <salah.triki@xxxxxxxxx>
> ---
>  drivers/iio/temperature/tmp117.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/temperature/tmp117.c b/drivers/iio/temperature/tmp117.c
> index 6bc18616ad15..7d74f401bb80 100644
> --- a/drivers/iio/temperature/tmp117.c
> +++ b/drivers/iio/temperature/tmp117.c
> @@ -95,15 +95,20 @@ static int tmp117_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec
>  {
>  	struct tmp117_data *data = iio_priv(indio_dev);
>  	s16 off;
> +	int ret;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_CALIBBIAS:
>  		off = clamp_t(int, val, S16_MIN, S16_MAX);
>  		if (off == data->calibbias)
>  			return 0;

Add a blank line here.

> +		ret = i2c_smbus_write_word_swapped(data->client, TMP117_REG_TEMP_OFFSET, off);
> +

And remove the blank line here - return value checks should be grouped
with the function we're checking.

> +		if (ret)
> +			return ret;
> +
>  		data->calibbias = off;
> -		return i2c_smbus_write_word_swapped(data->client,
> -						TMP117_REG_TEMP_OFFSET, off);
> +		return 0;
>  
>  	default:
>  		return -EINVAL;



-- 
Kind regards,
Joshua Crofts