[PATCH v2] iio: temperature: ltc2983: pass leak detector type explicitly

[PATCH v2] iio: temperature: ltc2983: pass leak detector type explicitly

[Carlos Casadiego via B4 Relay]

From: Carlos Casadiego <cdcp206@gmail.com>

__ltc2983_custom_sensor_new() uses propname both to select the firmware
property to read and to determine whether the custom sensor is a leak
detector.

Pass this information explicitly from the caller instead of deriving
the sensor type from the firmware property name. This keeps propname
limited to identifying the property and preserves the existing
conversion behavior.

As a side effect, this also avoids the -Wstring-compare warning reported
by the kernel test robot for callers where GCC can determine that the
property name cannot match "adi,custom-leak-detector".

Fixes: 3dd0c048409e ("iio: temperature: ltc2983: Add support for ADT7604")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202609120045.OxEsKLIn-lkp@intel.com/
Signed-off-by: Carlos Casadiego <cdcp206@gmail.com>
---
Changes in v2:
- Reframe the change around passing the leak detector type explicitly,
  with the compiler warning as a side effect.
- Drop const qualifiers from bool parameters as suggested by Andy
  Shevchenko.
- Link to v1: https://patch.msgid.link/20260929-iio-ltc2983-fix-string-compare-v1-1-d67d612d6ddd@gmail.com

To: Nuno Sá <nuno.sa@analog.com>
To: Jonathan Cameron <jic23@kernel.org>
To: David Lechner <dlechner@baylibre.com>
To: Andy Shevchenko <andy@kernel.org>
To: Liviu Stan <liviu.stan@analog.com>
Cc: linux-iio@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/iio/temperature/ltc2983.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/temperature/ltc2983.c b/drivers/iio/temperature/ltc2983.c
index 6efb5252a773..6abaf64c8498 100644
--- a/drivers/iio/temperature/ltc2983.c
+++ b/drivers/iio/temperature/ltc2983.c
@@ -471,8 +471,9 @@ static int __ltc2983_chan_custom_sensor_assign(struct ltc2983_data *st,
 
 static struct ltc2983_custom_sensor *
 __ltc2983_custom_sensor_new(struct ltc2983_data *st, const struct fwnode_handle *fn,
-			    const char *propname, const bool is_steinhart,
-			    const u32 resolution, const bool has_signed)
+			    const char *propname, bool is_steinhart,
+			    const u32 resolution, bool has_signed,
+			    bool is_leak_detector)
 {
 	struct ltc2983_custom_sensor *new_custom;
 	struct device *dev = &st->spi->dev;
@@ -545,7 +546,7 @@ __ltc2983_custom_sensor_new(struct ltc2983_data *st, const struct fwnode_handle
 			 * to µK so __convert_to_raw() produces the correct hardware
 			 * encoding: P + 273.15 K.
 			 */
-			if ((index % 2) != 0 && !strcmp(propname, "adi,custom-leak-detector"))
+			if ((index % 2) != 0 && is_leak_detector)
 				temp = temp * 1000000 + 273150000;
 
 			if ((index % 2) != 0)
@@ -836,7 +837,7 @@ ltc2983_thermocouple_new(const struct fwnode_handle *child, struct ltc2983_data
 
 		thermo->custom = __ltc2983_custom_sensor_new(st, child,
 							     propname, false,
-							     16384, true);
+							     16384, true, false);
 		if (IS_ERR(thermo->custom))
 			return ERR_CAST(thermo->custom);
 	}
@@ -950,7 +951,8 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
 	if (sensor->type == LTC2983_SENSOR_RTD_CUSTOM) {
 		rtd->custom = __ltc2983_custom_sensor_new(st, child,
 							  "adi,custom-rtd",
-							  false, 2048, false);
+							  false, 2048, false,
+							  false);
 		if (IS_ERR(rtd->custom))
 			return ERR_CAST(rtd->custom);
 	}
@@ -1068,7 +1070,7 @@ ltc2983_thermistor_new(const struct fwnode_handle *child, struct ltc2983_data *s
 		thermistor->custom = __ltc2983_custom_sensor_new(st, child,
 								 propname,
 								 steinhart,
-								 64, false);
+								 64, false, false);
 		if (IS_ERR(thermistor->custom))
 			return ERR_CAST(thermistor->custom);
 	}
@@ -1184,7 +1186,7 @@ ltc2983_copper_trace_new(const struct fwnode_handle *child, struct ltc2983_data
 						 "adi,custom-copper-trace is required for >1 ohm copper trace\n");
 
 		ct->custom = __ltc2983_custom_sensor_new(st, child, "adi,custom-copper-trace",
-							 false, 2048, false);
+							 false, 2048, false, false);
 		if (IS_ERR(ct->custom))
 			return ERR_CAST(ct->custom);
 
@@ -1275,7 +1277,7 @@ ltc2983_leak_detector_new(const struct fwnode_handle *child, struct ltc2983_data
 					 "adi,custom-leak-detector is required for leak detectors\n");
 
 	ld->custom = __ltc2983_custom_sensor_new(st, child, "adi,custom-leak-detector",
-						 false, 16, false);
+						 false, 16, false, true);
 	if (IS_ERR(ld->custom))
 		return ERR_CAST(ld->custom);
 
@@ -1488,7 +1490,7 @@ static struct ltc2983_sensor *ltc2983_temp_new(struct fwnode_handle *child,
 					 sensor->chan);
 
 	temp->custom = __ltc2983_custom_sensor_new(st, child, "adi,custom-temp",
-						   false, 4096, true);
+						   false, 4096, true, false);
 	if (IS_ERR(temp->custom))
 		return ERR_CAST(temp->custom);
 

---
base-commit: d2f2868d2f487b418f68db2ef5bd7cf41722ee68
change-id: 20260929-iio-ltc2983-fix-string-compare-c919244f019d

Best regards,
--  
Carlos Casadiego <cdcp206@gmail.com>

Re: [PATCH v2] iio: temperature: ltc2983: pass leak detector type explicitly

[Andy Shevchenko]

On Fri, Oct 02, 2026 at 11:44:50AM -0500, Carlos Casadiego via B4 Relay wrote:

> __ltc2983_custom_sensor_new() uses propname both to select the firmware
> property to read and to determine whether the custom sensor is a leak
> detector.
> 
> Pass this information explicitly from the caller instead of deriving
> the sensor type from the firmware property name. This keeps propname
> limited to identifying the property and preserves the existing
> conversion behavior.
> 
> As a side effect, this also avoids the -Wstring-compare warning reported
> by the kernel test robot for callers where GCC can determine that the
> property name cannot match "adi,custom-leak-detector".

Reviewed-by: Andy Shevchenko <andy@kernel.org>

...

> -			if ((index % 2) != 0 && !strcmp(propname, "adi,custom-leak-detector"))
> +			if ((index % 2) != 0 && is_leak_detector)
>  				temp = temp * 1000000 + 273150000;

A side note for the further changes: We have ABSOLUTE_ZERO_MILLICELSIUS
that can be used here.

...

Since Arnd also submitted similar fix, it would be good to Cc him. And in
general, if there is a clash with the patches addressing same issue, Cc all
other authors.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2] iio: temperature: ltc2983: pass leak detector type explicitly

[Carlos Casadiego]

Thanks for the review.

Noted on ABSOLUTE_ZERO_MILLICELSIUS for a follow-up change.

Cc'ing Arnd as his patch overlaps with this one. I'll wait for the maintainers' preference on the two approaches.

Thanks,
Carlos

En Sat, Oct 03, 2026 at 10:20:41PM +0300, Andy Shevchenko escribió:
> On Fri, Oct 02, 2026 at 11:44:50AM -0500, Carlos Casadiego via B4 Relay wrote:
> 
> > __ltc2983_custom_sensor_new() uses propname both to select the firmware
> > property to read and to determine whether the custom sensor is a leak
> > detector.
> > 
> > Pass this information explicitly from the caller instead of deriving
> > the sensor type from the firmware property name. This keeps propname
> > limited to identifying the property and preserves the existing
> > conversion behavior.
> > 
> > As a side effect, this also avoids the -Wstring-compare warning reported
> > by the kernel test robot for callers where GCC can determine that the
> > property name cannot match "adi,custom-leak-detector".
> 
> Reviewed-by: Andy Shevchenko <andy@kernel.org>
> 
> ...
> 
> > -			if ((index % 2) != 0 && !strcmp(propname, "adi,custom-leak-detector"))
> > +			if ((index % 2) != 0 && is_leak_detector)
> >  				temp = temp * 1000000 + 273150000;
> 
> A side note for the further changes: We have ABSOLUTE_ZERO_MILLICELSIUS
> that can be used here.
> 
> ...
> 
> Since Arnd also submitted similar fix, it would be good to Cc him. And in
> general, if there is a clash with the patches addressing same issue, Cc all
> other authors.
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
>