Re: [PATCH] iio: adc: ti-ads1018: fix type overflow for data rate

["Kurt Borja" <kuurtb@gmail.com>]

Hi Chunyang,

On Wed Mar 4, 2026 at 11:15 PM -03, Chunyang Chen wrote:
> The variable 'drate' is currently defined as u8. However, the data rate
> values in ads1018 can reach up to 3300 Hz (e.g., in ads1018_data_rate[]),
> which exceeds the maximum value of 255 that a u8 can hold.
>
> Change the type of 'drate' to u16 to prevent integer overflow and
> ensure the data rate is handled correctly.

Good catch -- thanks!

Interestingly, my SPI controller has so much latency that I didn't catch
this while developing :/

>
> Signed-off-by: Chunyang Chen <chenchunyang0908@gmail.com>
> ---
>  drivers/iio/adc/ti-ads1018.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iio/adc/ti-ads1018.c b/drivers/iio/adc/ti-ads1018.c
> index 6246b3cab..049b8c00f 100644
> --- a/drivers/iio/adc/ti-ads1018.c
> +++ b/drivers/iio/adc/ti-ads1018.c
> @@ -249,7 +249,7 @@ static int ads1018_single_shot(struct ads1018 *ads1018,
>  			       struct iio_chan_spec const *chan, u16 *cnv)
>  {
>  	u8 max_drate_mode = ads1018->chip_info->num_data_rate_mode_to_hz - 1;
> -	u8 drate = ads1018->chip_info->data_rate_mode_to_hz[max_drate_mode];
> +	u16 drate = ads1018->chip_info->data_rate_mode_to_hz[max_drate_mode];

data_rate_mode_to_hz[] is u32 so I prefer for this to be u32. This also
kinda matches ads1018_calc_delay() which takes unsigned int.

I'm a bit disturbed by the type inconsistency here...

>  	u8 pga_mode = ads1018->chan_data[chan->scan_index].pga_mode;
>  	struct spi_transfer xfer[2] = {
>  		{

-- 
Thanks,
 ~ Kurt