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

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

[Chunyang Chen]

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.

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];
 	u8 pga_mode = ads1018->chan_data[chan->scan_index].pga_mode;
 	struct spi_transfer xfer[2] = {
 		{
-- 
2.34.1

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

[Kurt Borja]

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

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

[Andy Shevchenko]

On Thu, Mar 05, 2026 at 10:15:50AM +0800, 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.

Needs Fixes tag.

-- 
With Best Regards,
Andy Shevchenko

[PATCH v2] iio: adc: ti-ads1018: fix type overflow for data rate

[Chunyang Chen]

The variable 'drate' is currently defined as u8. However, the data rate
values in ads1018 can reach up to 3300 Hz, which exceeds the maximum
value of 255 that a u8 can hold.

Change the type of 'drate' to u32 to match the data_rate_mode_to_hz
array definition and ensure the data rate is handled correctly.

Fixes: bf0bba486b5b ("iio: adc: ti-ads1018: add ti-ads1018 driver")
Signed-off-by: Chunyang Chen <chenchunyang0908@gmail.com>

---
v2:
- Change drate type to u32 as suggested by Kurt.
- Add Fixes tag as requested by Andy.
---
 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..0780abd0d 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];
+	u32 drate = ads1018->chip_info->data_rate_mode_to_hz[max_drate_mode];
 	u8 pga_mode = ads1018->chan_data[chan->scan_index].pga_mode;
 	struct spi_transfer xfer[2] = {
 		{
-- 
2.34.1

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

[Chunyang Chen]

Hi Kurt, Andy,

Thanks for your review and suggestions!
I have sent out the v2 patch, which addresses the following:

On Thu, Mar 5, 2026, Kurt Borja wrote:
> 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.

Changed 'drate' type to u32 to match the array definition and maintain
consistency, as suggested by Kurt.

On Thu, Mar 5, 2026, Andy Shevchenko wrote:
> Needs Fixes tag.

Added the Fixes tag as requested by Andy.

Best regards,
Chunyang Chen

Re: [PATCH v2] iio: adc: ti-ads1018: fix type overflow for data rate

[Kurt Borja]

On Thu Mar 5, 2026 at 9:43 AM -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, which exceeds the maximum
> value of 255 that a u8 can hold.
>
> Change the type of 'drate' to u32 to match the data_rate_mode_to_hz
> array definition and ensure the data rate is handled correctly.
>
> Fixes: bf0bba486b5b ("iio: adc: ti-ads1018: add ti-ads1018 driver")
> Signed-off-by: Chunyang Chen <chenchunyang0908@gmail.com>

Reviewed-by: Kurt Borja <kuurtb@gmail.com>

>
> ---
> v2:
> - Change drate type to u32 as suggested by Kurt.
> - Add Fixes tag as requested by Andy.
> ---
>  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..0780abd0d 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];
> +	u32 drate = ads1018->chip_info->data_rate_mode_to_hz[max_drate_mode];
>  	u8 pga_mode = ads1018->chan_data[chan->scan_index].pga_mode;
>  	struct spi_transfer xfer[2] = {
>  		{

-- 
Thanks,
 ~ Kurt

Re: [PATCH v2] iio: adc: ti-ads1018: fix type overflow for data rate

[Andy Shevchenko]

On Thu, Mar 05, 2026 at 08:43:02PM +0800, Chunyang Chen wrote:
> The variable 'drate' is currently defined as u8. However, the data rate
> values in ads1018 can reach up to 3300 Hz, which exceeds the maximum
> value of 255 that a u8 can hold.
> 
> Change the type of 'drate' to u32 to match the data_rate_mode_to_hz
> array definition and ensure the data rate is handled correctly.
> 
> Fixes: bf0bba486b5b ("iio: adc: ti-ads1018: add ti-ads1018 driver")
> Signed-off-by: Chunyang Chen <chenchunyang0908@gmail.com>

New version — new email thread.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] iio: adc: ti-ads1018: fix type overflow for data rate

[Jonathan Cameron]

On Fri, 6 Mar 2026 14:08:15 +0200
Andy Shevchenko <andriy.shevchenko@intel.com> wrote:

> On Thu, Mar 05, 2026 at 08:43:02PM +0800, Chunyang Chen wrote:
> > The variable 'drate' is currently defined as u8. However, the data rate
> > values in ads1018 can reach up to 3300 Hz, which exceeds the maximum
> > value of 255 that a u8 can hold.
> > 
> > Change the type of 'drate' to u32 to match the data_rate_mode_to_hz
> > array definition and ensure the data rate is handled correctly.
> > 
> > Fixes: bf0bba486b5b ("iio: adc: ti-ads1018: add ti-ads1018 driver")
> > Signed-off-by: Chunyang Chen <chenchunyang0908@gmail.com>  
> 
> New version — new email thread.
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
> 

Applied to the fixes-togreg branch of iio.git

Thanks,

Jonathan

Re: [PATCH v2] iio: adc: ti-ads1018: fix type overflow for data rate

[Jonathan Cameron]

On Thu,  5 Mar 2026 20:43:02 +0800
Chunyang Chen <chenchunyang0908@gmail.com> wrote:

> The variable 'drate' is currently defined as u8. However, the data rate
> values in ads1018 can reach up to 3300 Hz, which exceeds the maximum
> value of 255 that a u8 can hold.
> 
> Change the type of 'drate' to u32 to match the data_rate_mode_to_hz
> array definition and ensure the data rate is handled correctly.
> 
> Fixes: bf0bba486b5b ("iio: adc: ti-ads1018: add ti-ads1018 driver")
The patch name in this fixes tag is wrong.  I fixed up.

J
> Signed-off-by: Chunyang Chen <chenchunyang0908@gmail.com>
> 
> ---
> v2:
> - Change drate type to u32 as suggested by Kurt.
> - Add Fixes tag as requested by Andy.
> ---
>  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..0780abd0d 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];
> +	u32 drate = ads1018->chip_info->data_rate_mode_to_hz[max_drate_mode];
>  	u8 pga_mode = ads1018->chan_data[chan->scan_index].pga_mode;
>  	struct spi_transfer xfer[2] = {
>  		{

Re: [PATCH v2] iio: adc: ti-ads1018: fix type overflow for data rate

[Chunyang Chen]

Hi Jonathan, Andy, Kurt,

Thanks for the review and for applying this patch to iio/fixes-togreg!
Also, thanks Jonathan for fixing up the patch name in the Fixes tag.

Best regards,
Chunyang Chen