[PATCH] iio: accel: fix ADXL355 temperature signature value

[PATCH] iio: accel: fix ADXL355 temperature signature value

[Andrej Valek]

From: "Valek Andrej <andrej.v@skyrain.eu>"

Temperature was wrongly represented as 12-bit signature, confirmed by DS.
Even if the temperature is negative, the value in the register stays
unsigned.

Signed-off-by: Valek Andrej <andrej.v@skyrain.eu>
---
 drivers/iio/accel/adxl355_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/accel/adxl355_core.c b/drivers/iio/accel/adxl355_core.c
index 1c1d64d5cbcb2..8f90c58f41008 100644
--- a/drivers/iio/accel/adxl355_core.c
+++ b/drivers/iio/accel/adxl355_core.c
@@ -745,7 +745,7 @@ static const struct iio_chan_spec adxl355_channels[] = {
 				      BIT(IIO_CHAN_INFO_OFFSET),
 		.scan_index = 3,
 		.scan_type = {
-			.sign = 's',
+			.sign = 'u',
 			.realbits = 12,
 			.storagebits = 16,
 			.endianness = IIO_BE,
-- 
2.34.1

Re: [PATCH] iio: accel: fix ADXL355 temperature signature value

[David Lechner]

On 3/13/26 4:24 AM, Andrej Valek wrote:
> From: "Valek Andrej <andrej.v@skyrain.eu>"
> 
> Temperature was wrongly represented as 12-bit signature, confirmed by DS.

signature == signed integer?

DS == datasheet?

> Even if the temperature is negative, the value in the register stays
> unsigned.

And IIO_CHAN_INFO_OFFSET will be negative.

> 
> Signed-off-by: Valek Andrej <andrej.v@skyrain.eu>
> ---
>  drivers/iio/accel/adxl355_core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/accel/adxl355_core.c b/drivers/iio/accel/adxl355_core.c
> index 1c1d64d5cbcb2..8f90c58f41008 100644
> --- a/drivers/iio/accel/adxl355_core.c
> +++ b/drivers/iio/accel/adxl355_core.c
> @@ -745,7 +745,7 @@ static const struct iio_chan_spec adxl355_channels[] = {
>  				      BIT(IIO_CHAN_INFO_OFFSET),
>  		.scan_index = 3,
>  		.scan_type = {
> -			.sign = 's',
> +			.sign = 'u',
>  			.realbits = 12,
>  			.storagebits = 16,
>  			.endianness = IIO_BE,

Re: [PATCH] iio: accel: fix ADXL355 temperature signature value

[Andrej Valek]

Ah, I see, I described it wrongly.

On 14.03.2026 21:22, David Lechner wrote:
> On 3/13/26 4:24 AM, Andrej Valek wrote:
>> From: "Valek Andrej <andrej.v@skyrain.eu>"
>>
>> Temperature was wrongly represented as 12-bit signature, confirmed by DS.
> signature == signed integer?
Correct, temperature is wrongly represented as signed 12-bit number, 
while it has to be unsigned.
>
> DS == datasheet?
Yes
>
>> Even if the temperature is negative, the value in the register stays
>> unsigned.
> And IIO_CHAN_INFO_OFFSET will be negative.
Not sure what do you mean by this. I can only say, that output type was 
"be:s12/16>>0" and should be "be:u12/16>>0". So when some upper layer 
wanted to represent the number it "overflowed", while the bits have been 
masked.
>
>> Signed-off-by: Valek Andrej <andrej.v@skyrain.eu>
>> ---
>>   drivers/iio/accel/adxl355_core.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iio/accel/adxl355_core.c b/drivers/iio/accel/adxl355_core.c
>> index 1c1d64d5cbcb2..8f90c58f41008 100644
>> --- a/drivers/iio/accel/adxl355_core.c
>> +++ b/drivers/iio/accel/adxl355_core.c
>> @@ -745,7 +745,7 @@ static const struct iio_chan_spec adxl355_channels[] = {
>>   				      BIT(IIO_CHAN_INFO_OFFSET),
>>   		.scan_index = 3,
>>   		.scan_type = {
>> -			.sign = 's',
>> +			.sign = 'u',
>>   			.realbits = 12,
>>   			.storagebits = 16,
>>   			.endianness = IIO_BE,
>
>
Conclusion = Should I send a new version with "fixed" description?

BR,
Andy

Re: [PATCH] iio: accel: fix ADXL355 temperature signature value

[David Lechner]

On 3/15/26 10:35 AM, Andrej Valek wrote:
> Ah, I see, I described it wrongly.
> 
> On 14.03.2026 21:22, David Lechner wrote:
>> On 3/13/26 4:24 AM, Andrej Valek wrote:
>>> From: "Valek Andrej <andrej.v@skyrain.eu>"
>>>
>>> Temperature was wrongly represented as 12-bit signature, confirmed by DS.
>> signature == signed integer?
> Correct, temperature is wrongly represented as signed 12-bit number, while it has to be unsigned.
>>
>> DS == datasheet?
> Yes
>>
>>> Even if the temperature is negative, the value in the register stays
>>> unsigned.
>> And IIO_CHAN_INFO_OFFSET will be negative.
> Not sure what do you mean by this. I can only say, that output type was "be:s12/16>>0" and should be "be:u12/16>>0". So when some upper layer wanted to represent the number it "overflowed", while the bits have been masked.

Mostly I was talking to myself on this point. No action is needed here.

>>
>>> Signed-off-by: Valek Andrej <andrej.v@skyrain.eu>
>>> ---
>>>   drivers/iio/accel/adxl355_core.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/iio/accel/adxl355_core.c b/drivers/iio/accel/adxl355_core.c
>>> index 1c1d64d5cbcb2..8f90c58f41008 100644
>>> --- a/drivers/iio/accel/adxl355_core.c
>>> +++ b/drivers/iio/accel/adxl355_core.c
>>> @@ -745,7 +745,7 @@ static const struct iio_chan_spec adxl355_channels[] = {
>>>                         BIT(IIO_CHAN_INFO_OFFSET),
>>>           .scan_index = 3,
>>>           .scan_type = {
>>> -            .sign = 's',
>>> +            .sign = 'u',
>>>               .realbits = 12,
>>>               .storagebits = 16,
>>>               .endianness = IIO_BE,
>>
>>
> Conclusion = Should I send a new version with "fixed" description?

Sometimes, for small tweaks, Jonathan will just fix it while applying the
patch. So wait for for his feedback.

You can also see the status of the patch in patchwork at [1]. If the State
changes to "Changes requested", then you know a new version is expected.
Right now, it says "New" which means he hasn't looked at it or made a
decision yet.


[1]: https://patchwork.kernel.org/project/linux-iio/patch/20260313092413.35912-1-andy@skyrain.eu/

> 
> BR,
> Andy

Re: [PATCH] iio: accel: fix ADXL355 temperature signature value

[Jonathan Cameron]

On Sun, 15 Mar 2026 11:18:18 -0500
David Lechner <dlechner@baylibre.com> wrote:

> On 3/15/26 10:35 AM, Andrej Valek wrote:
> > Ah, I see, I described it wrongly.
> > 
> > On 14.03.2026 21:22, David Lechner wrote:  
> >> On 3/13/26 4:24 AM, Andrej Valek wrote:  
> >>> From: "Valek Andrej <andrej.v@skyrain.eu>"
> >>>
> >>> Temperature was wrongly represented as 12-bit signature, confirmed by DS.  
> >> signature == signed integer?  
> > Correct, temperature is wrongly represented as signed 12-bit number, while it has to be unsigned.  
> >>
> >> DS == datasheet?  
> > Yes  
> >>  
> >>> Even if the temperature is negative, the value in the register stays
> >>> unsigned.  
> >> And IIO_CHAN_INFO_OFFSET will be negative.  
> > Not sure what do you mean by this. I can only say, that output type was "be:s12/16>>0" and should be "be:u12/16>>0". So when some upper layer wanted to represent the number it "overflowed", while the bits have been masked.  
> 
> Mostly I was talking to myself on this point. No action is needed here.
> 
> >>  
> >>> Signed-off-by: Valek Andrej <andrej.v@skyrain.eu>
> >>> ---
> >>>   drivers/iio/accel/adxl355_core.c | 2 +-
> >>>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/iio/accel/adxl355_core.c b/drivers/iio/accel/adxl355_core.c
> >>> index 1c1d64d5cbcb2..8f90c58f41008 100644
> >>> --- a/drivers/iio/accel/adxl355_core.c
> >>> +++ b/drivers/iio/accel/adxl355_core.c
> >>> @@ -745,7 +745,7 @@ static const struct iio_chan_spec adxl355_channels[] = {
> >>>                         BIT(IIO_CHAN_INFO_OFFSET),
> >>>           .scan_index = 3,
> >>>           .scan_type = {
> >>> -            .sign = 's',
> >>> +            .sign = 'u',
> >>>               .realbits = 12,
> >>>               .storagebits = 16,
> >>>               .endianness = IIO_BE,  
> >>
> >>  
> > Conclusion = Should I send a new version with "fixed" description?  
> 
> Sometimes, for small tweaks, Jonathan will just fix it while applying the
> patch. So wait for for his feedback.
> 
> You can also see the status of the patch in patchwork at [1]. If the State
> changes to "Changes requested", then you know a new version is expected.
> Right now, it says "New" which means he hasn't looked at it or made a
> decision yet.
> 
> 
> [1]: https://patchwork.kernel.org/project/linux-iio/patch/20260313092413.35912-1-andy@skyrain.eu/

Busy few weeks. Catching up now.

This also needs a fixes tag to indicate how far back we should be looking
to backport it.

Looks like it was all the way so I've added one.
Fixes: 12ed27863ea3 ("iio: accel: Add driver support for ADXL355")

Applied to the fixes-togreg branch of iio.git and marked for stable.

Thanks,

Jonathan


> 
> > 
> > BR,
> > Andy  
> 
>