[PATCH v2 0/4] Add LTC2495 support

[PATCH v2 0/4] Add LTC2495 support

[Yusuf Alper Bilgin]

Hi All,

This is the v2 of the patch series to add support for the LTC2495 ADC to
the ltc2497 driver and to enable the internal temperature channel for
the LTC2495 and LTC2499.

Many thanks to Andy Shevchenko and Krzysztof Kozlowski for their
detailed and helpful reviews on v1. I believe I've addressed all
feedbacks in this version.

Best Regards,

Alper

Signed-off-by: Yusuf Alper Bilgin <y.alperbilgin@gmail.com>
---
Changes in v2:
  - Rewrote all commit messages to use the imperative mood.
  - Added a justification for the new compatible string to the device
    tree binding commit message.
  - Removed all unrelated whitespace and formatting changes.
  - Removed redundant explicit `false` initializers from structs.
  - Replaced the magic number for Kelvin conversion with a define.
  - Improved comments for defines and temperature scaling constants.
  - Renamed confusing macros and struct fields to be more descriptive.
  - Replaced dynamic channel allocation with a static array approach
    using a shared macro to improve readability.
  - Optimized data structure layouts based on pahole output to remove
    memory holes.
  - Link to v1: https://lore.kernel.org/r/20250812-ltc2495-v1-0-7bf4c6feec2e@gmail.com
---
Implementation Notes
 - checkpatch warning: The new static array approach uses a shared macro
   for the common channels (`LTC2497_CHANNELS`), which triggers a
   checkpatch.pl warning: "Macros with complex values should be enclosed
   in parentheses". However, this will cause a compilitaion error, as an
   initializer list cannot be parenthesized.
 - uV to mV conversion: I could not find a standard macro, so a manual
   division is used for now. This could be a point of future
   improvement.

---
Yusuf Alper Bilgin (4):
      dt-bindings: iio: adc: ltc2497: add lltc,ltc2495 bindings
      iio: adc: ltc2497: add support for LTC2495
      iio: adc: ltc2497: add temperature sensor support
      iio: adc: ltc2497: reorder ltc2497core_driverdata members to remove hole

 .../devicetree/bindings/iio/adc/lltc,ltc2497.yaml  |   3 +
 drivers/iio/adc/ltc2497-core.c                     | 140 +++++++++++++++------
 drivers/iio/adc/ltc2497.c                          |  35 +++++-
 drivers/iio/adc/ltc2497.h                          |  23 +++-
 4 files changed, 158 insertions(+), 43 deletions(-)
---
base-commit: acbbb5a20971089064ca6b271dd251e629be8d4d
change-id: 20250811-ltc2495-572817c13fd3

Best regards,
-- 
Yusuf Alper Bilgin <y.alperbilgin@gmail.com>

[PATCH v2 1/4] dt-bindings: iio: adc: ltc2497: add lltc,ltc2495 bindings

[Yusuf Alper Bilgin]

Update the binding documentation for LTC2497 to include LTC2495 to
enable support for its internal temperature sensor, which requires a
different I2C command format and a new IIO channel.

Signed-off-by: Yusuf Alper Bilgin <y.alperbilgin@gmail.com>
---
 Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml b/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml
index 5cc6a96840778473895f436b7e2627d6240b254b..2a3e3dcc6ca7a48a0fccb88d8d42fee34efcff73 100644
--- a/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/lltc,ltc2497.yaml
@@ -17,11 +17,13 @@ description: |
 
     https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf
 
+  LTC2495:
   LTC2497:
   LTC2499:
     16bit ADC supporting up to 16 single ended or 8 differential inputs.
     I2C interface.
 
+    https://www.analog.com/media/en/technical-documentation/data-sheets/2495fe.pdf
     https://www.analog.com/media/en/technical-documentation/data-sheets/2497fb.pdf
     https://www.analog.com/media/en/technical-documentation/data-sheets/2499fe.pdf
 
@@ -29,6 +31,7 @@ properties:
   compatible:
     enum:
       - lltc,ltc2309
+      - lltc,ltc2495
       - lltc,ltc2497
       - lltc,ltc2499
 

-- 
2.43.0

[PATCH v2 2/4] iio: adc: ltc2497: add support for LTC2495

[Yusuf Alper Bilgin]

Update the LTC2497 driver to also support the LTC2495.

Signed-off-by: Yusuf Alper Bilgin <y.alperbilgin@gmail.com>
---
 drivers/iio/adc/ltc2497.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c
index eb9d521e86e54def0493ea0e81f63b37900c56a5..8f4665547b5b0d32084599f8557c40102c37a4ce 100644
--- a/drivers/iio/adc/ltc2497.c
+++ b/drivers/iio/adc/ltc2497.c
@@ -19,6 +19,7 @@
 #include "ltc2497.h"
 
 enum ltc2497_chip_type {
+	TYPE_LTC2495,
 	TYPE_LTC2497,
 	TYPE_LTC2499,
 };
@@ -131,6 +132,10 @@ static void ltc2497_remove(struct i2c_client *client)
 }
 
 static const struct ltc2497_chip_info ltc2497_info[] = {
+	[TYPE_LTC2495] = {
+		.resolution = 16,
+		.name = "ltc2495",
+	},
 	[TYPE_LTC2497] = {
 		.resolution = 16,
 		.name = NULL,
@@ -142,6 +147,7 @@ static const struct ltc2497_chip_info ltc2497_info[] = {
 };
 
 static const struct i2c_device_id ltc2497_id[] = {
+	{ "ltc2495", (kernel_ulong_t)&ltc2497_info[TYPE_LTC2495] },
 	{ "ltc2497", (kernel_ulong_t)&ltc2497_info[TYPE_LTC2497] },
 	{ "ltc2499", (kernel_ulong_t)&ltc2497_info[TYPE_LTC2499] },
 	{ }
@@ -149,6 +155,7 @@ static const struct i2c_device_id ltc2497_id[] = {
 MODULE_DEVICE_TABLE(i2c, ltc2497_id);
 
 static const struct of_device_id ltc2497_of_match[] = {
+	{ .compatible = "lltc,ltc2495", .data = &ltc2497_info[TYPE_LTC2495] },
 	{ .compatible = "lltc,ltc2497", .data = &ltc2497_info[TYPE_LTC2497] },
 	{ .compatible = "lltc,ltc2499", .data = &ltc2497_info[TYPE_LTC2499] },
 	{ }

-- 
2.43.0

[PATCH v2 3/4] iio: adc: ltc2497: add temperature sensor support

[Yusuf Alper Bilgin]

Support for reading the internal temperature sensor on LTC2495 and
LTC2499 via a standard IIO temperature channel.

Signed-off-by: Yusuf Alper Bilgin <y.alperbilgin@gmail.com>
---
 drivers/iio/adc/ltc2497-core.c | 140 ++++++++++++++++++++++++++++++-----------
 drivers/iio/adc/ltc2497.c      |  28 ++++++++-
 drivers/iio/adc/ltc2497.h      |  17 ++++-
 3 files changed, 145 insertions(+), 40 deletions(-)

diff --git a/drivers/iio/adc/ltc2497-core.c b/drivers/iio/adc/ltc2497-core.c
index 2dc5c704426949a4ec62c42591d6c2c40ffb79cc..0e21d5f59e6108be8b5d79bd706425278043b44d 100644
--- a/drivers/iio/adc/ltc2497-core.c
+++ b/drivers/iio/adc/ltc2497-core.c
@@ -18,6 +18,7 @@
 #define LTC2497_SGL			BIT(4)
 #define LTC2497_DIFF			0
 #define LTC2497_SIGN			BIT(3)
+#define LTC2497_KELVIN_TO_CELCIUS	273
 
 static int ltc2497core_wait_conv(struct ltc2497core_driverdata *ddata)
 {
@@ -95,10 +96,53 @@ static int ltc2497core_read_raw(struct iio_dev *indio_dev,
 		if (ret < 0)
 			return ret;
 
-		*val = ret / 1000;
-		*val2 = ddata->chip_info->resolution + 1;
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			*val = ret / 1000;
+			*val2 = ddata->chip_info->resolution + 1;
+
+			return IIO_VAL_FRACTIONAL_LOG2;
+
+		case IIO_TEMP:
+			if (!ddata->chip_info->has_temp_channel)
+				return -EINVAL;
+
+			/*
+			 * The datasheet formula to get Temperature in Celsius is:
+			 * Temp_C = (DATAOUT * Vref_V / temp_scale) - 273
+			 *
+			 * To match the IIO framework's model of (raw + offset) * scale,
+			 * and to get the final result in millidegrees Celsius:
+			 *
+			 * Temp_mC = ((DATAOUT * Vref_mV / temp_scale_mV) - 273) * 1000
+			 * Temp_mC = (DATAOUT - (273 * temp_scale_mV / Vref_mv)) * 1000 *
+			 *           Vref_mV / temp_scale_mV
+			 *
+			 * This gives us:
+			 * scale  = Vref_mV * 1000 / temp_scale_mV
+			 * offset = -273 * temp_scale / Vref_mV
+			 */
+			*val = ret;
+			*val2 = ddata->chip_info->temp_scale_mV;
+
+			return IIO_VAL_FRACTIONAL;
+
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_OFFSET:
+		if (chan->type != IIO_TEMP)
+			return -EINVAL;
+
+		/* see the calculation above. Offset with (-273 * temp_scale / Vref) */
+		ret = regulator_get_voltage(ddata->ref);
+		if (ret < 0)
+			return ret;
 
-		return IIO_VAL_FRACTIONAL_LOG2;
+		*val = -LTC2497_KELVIN_TO_CELCIUS * ddata->chip_info->temp_scale_mV;
+		*val2 = ret / 1000;
+
+		return IIO_VAL_FRACTIONAL;
 
 	default:
 		return -EINVAL;
@@ -126,39 +170,55 @@ static int ltc2497core_read_raw(struct iio_dev *indio_dev,
 	.differential = 1, \
 }
 
+#define LTC2497_T_CHAN {									\
+	.type = IIO_TEMP,									\
+	.channel = 0,										\
+	.address = (LTC2497_ENABLE_TEMPERATURE_CONV),						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),						\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),	\
+}
+
+#define LTC2497_CHANNELS \
+	LTC2497_CHAN(0, LTC2497_SGL, "CH0"),			\
+	LTC2497_CHAN(1, LTC2497_SGL, "CH1"),			\
+	LTC2497_CHAN(2, LTC2497_SGL, "CH2"),			\
+	LTC2497_CHAN(3, LTC2497_SGL, "CH3"),			\
+	LTC2497_CHAN(4, LTC2497_SGL, "CH4"),			\
+	LTC2497_CHAN(5, LTC2497_SGL, "CH5"),			\
+	LTC2497_CHAN(6, LTC2497_SGL, "CH6"),			\
+	LTC2497_CHAN(7, LTC2497_SGL, "CH7"),			\
+	LTC2497_CHAN(8, LTC2497_SGL, "CH8"),			\
+	LTC2497_CHAN(9, LTC2497_SGL, "CH9"),			\
+	LTC2497_CHAN(10, LTC2497_SGL, "CH10"),			\
+	LTC2497_CHAN(11, LTC2497_SGL, "CH11"),			\
+	LTC2497_CHAN(12, LTC2497_SGL, "CH12"),			\
+	LTC2497_CHAN(13, LTC2497_SGL, "CH13"),			\
+	LTC2497_CHAN(14, LTC2497_SGL, "CH14"),			\
+	LTC2497_CHAN(15, LTC2497_SGL, "CH15"),			\
+	LTC2497_CHAN_DIFF(0, LTC2497_DIFF),			\
+	LTC2497_CHAN_DIFF(1, LTC2497_DIFF),			\
+	LTC2497_CHAN_DIFF(2, LTC2497_DIFF),			\
+	LTC2497_CHAN_DIFF(3, LTC2497_DIFF),			\
+	LTC2497_CHAN_DIFF(4, LTC2497_DIFF),			\
+	LTC2497_CHAN_DIFF(5, LTC2497_DIFF),			\
+	LTC2497_CHAN_DIFF(6, LTC2497_DIFF),			\
+	LTC2497_CHAN_DIFF(7, LTC2497_DIFF),			\
+	LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN),	\
+	LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN),	\
+	LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN),	\
+	LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN),	\
+	LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN),	\
+	LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN),	\
+	LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN),	\
+	LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN)
+
 static const struct iio_chan_spec ltc2497core_channel[] = {
-	LTC2497_CHAN(0, LTC2497_SGL, "CH0"),
-	LTC2497_CHAN(1, LTC2497_SGL, "CH1"),
-	LTC2497_CHAN(2, LTC2497_SGL, "CH2"),
-	LTC2497_CHAN(3, LTC2497_SGL, "CH3"),
-	LTC2497_CHAN(4, LTC2497_SGL, "CH4"),
-	LTC2497_CHAN(5, LTC2497_SGL, "CH5"),
-	LTC2497_CHAN(6, LTC2497_SGL, "CH6"),
-	LTC2497_CHAN(7, LTC2497_SGL, "CH7"),
-	LTC2497_CHAN(8, LTC2497_SGL, "CH8"),
-	LTC2497_CHAN(9, LTC2497_SGL, "CH9"),
-	LTC2497_CHAN(10, LTC2497_SGL, "CH10"),
-	LTC2497_CHAN(11, LTC2497_SGL, "CH11"),
-	LTC2497_CHAN(12, LTC2497_SGL, "CH12"),
-	LTC2497_CHAN(13, LTC2497_SGL, "CH13"),
-	LTC2497_CHAN(14, LTC2497_SGL, "CH14"),
-	LTC2497_CHAN(15, LTC2497_SGL, "CH15"),
-	LTC2497_CHAN_DIFF(0, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(1, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(2, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(3, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(4, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(5, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(6, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(7, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN),
+	LTC2497_CHANNELS,
+};
+
+static const struct iio_chan_spec ltc2497core_channel_with_temperature[] = {
+	LTC2497_CHANNELS,
+	LTC2497_T_CHAN,
 };
 
 static const struct iio_info ltc2497core_info = {
@@ -182,8 +242,14 @@ int ltc2497core_probe(struct device *dev, struct iio_dev *indio_dev)
 
 	indio_dev->info = &ltc2497core_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->channels = ltc2497core_channel;
-	indio_dev->num_channels = ARRAY_SIZE(ltc2497core_channel);
+
+	if (ddata->chip_info->has_temp_channel) {
+		indio_dev->channels = ltc2497core_channel_with_temperature;
+		indio_dev->num_channels = ARRAY_SIZE(ltc2497core_channel_with_temperature);
+	} else {
+		indio_dev->channels = ltc2497core_channel;
+		indio_dev->num_channels = ARRAY_SIZE(ltc2497core_channel);
+	}
 
 	ret = ddata->result_and_measure(ddata, LTC2497_CONFIG_DEFAULT, NULL);
 	if (ret < 0)
diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c
index 8f4665547b5b0d32084599f8557c40102c37a4ce..07fced79aeead3778964b114d479fdcb643c16df 100644
--- a/drivers/iio/adc/ltc2497.c
+++ b/drivers/iio/adc/ltc2497.c
@@ -86,8 +86,28 @@ static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
 			return 0;
 	}
 
-	ret = i2c_smbus_write_byte(st->client,
-				   LTC2497_ENABLE | address);
+	/*
+	 * Chips with temperature sensor support (e.g., LTC2495/LTC2499)
+	 * require a two-byte command format to select any channel.
+	 *
+	 * To read the internal temperature, LTC2497_ENABLE_TEMPERATURE_CONV
+	 * is sent as the second byte. To read a voltage channel, LTC2497_EN2
+	 * is sent, which sets the default configuration: simultaneous 50/60Hz
+	 * rejection, 1x speed, and gain=1.
+	 *
+	 * Chips without this feature use a standard single-byte command.
+	 */
+	if (ddata->chip_info->has_temp_channel) {
+		if (address == LTC2497_ENABLE_TEMPERATURE_CONV)
+			ret = i2c_smbus_write_byte_data(st->client, LTC2497_ENABLE,
+							LTC2497_ENABLE_TEMPERATURE_CONV);
+		else
+			ret = i2c_smbus_write_byte_data(st->client, LTC2497_ENABLE | address,
+							LTC2497_EN2);
+	} else {
+		ret = i2c_smbus_write_byte(st->client, LTC2497_ENABLE | address);
+	}
+
 	if (ret)
 		dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
 			ERR_PTR(ret));
@@ -135,6 +155,8 @@ static const struct ltc2497_chip_info ltc2497_info[] = {
 	[TYPE_LTC2495] = {
 		.resolution = 16,
 		.name = "ltc2495",
+		.has_temp_channel = true,
+		.temp_scale_mV = 12250,
 	},
 	[TYPE_LTC2497] = {
 		.resolution = 16,
@@ -143,6 +165,8 @@ static const struct ltc2497_chip_info ltc2497_info[] = {
 	[TYPE_LTC2499] = {
 		.resolution = 24,
 		.name = "ltc2499",
+		.has_temp_channel = true,
+		.temp_scale_mV = 1570000,
 	},
 };
 
diff --git a/drivers/iio/adc/ltc2497.h b/drivers/iio/adc/ltc2497.h
index 64e81c95a3dd05911b6717c09ac0560c9f47f304..7f53bf8b8469d2371bb7ae64ce90a61beadba9ba 100644
--- a/drivers/iio/adc/ltc2497.h
+++ b/drivers/iio/adc/ltc2497.h
@@ -3,10 +3,25 @@
 #define LTC2497_ENABLE			0xA0
 #define LTC2497_CONFIG_DEFAULT		LTC2497_ENABLE
 #define LTC2497_CONVERSION_TIME_MS	150ULL
+#define LTC2497_EN2			BIT(7)
+/* Enable the internal temperature sensor */
+#define LTC2497_IM                      BIT(6)
+/* Second command byte value to initiate a temperature conversion */
+#define LTC2497_ENABLE_TEMPERATURE_CONV	(LTC2497_EN2 | LTC2497_IM)
 
 struct ltc2497_chip_info {
-	u32 resolution;
 	const char *name;
+	u32 resolution;
+	/*
+	 * Represents the datasheet constant from the temperature formula:
+	 * T_Kelvin = (DATAOUT * Vref) / temp_scale, where Vref is in Volts.
+	 *
+	 * To allow the driver to use Vref in millivolts for the calculation
+	 * and also to avoid floating points, this stored value represents the
+	 * datasheet constant scaled by 1000.
+	 */
+	u32 temp_scale_mV;
+	bool has_temp_channel;
 };
 
 struct ltc2497core_driverdata {

-- 
2.43.0

Re: [PATCH v2 3/4] iio: adc: ltc2497: add temperature sensor support

[Andy Shevchenko]

On Wed, Aug 13, 2025 at 6:54 PM Yusuf Alper Bilgin
<y.alperbilgin@gmail.com> wrote:
>
> Support for reading the internal temperature sensor on LTC2495 and
> LTC2499 via a standard IIO temperature channel.

...

> +#define LTC2497_KELVIN_TO_CELCIUS      273

Drop it, see below why.

...

> +               *val = -LTC2497_KELVIN_TO_CELCIUS * ddata->chip_info->temp_scale_mV;

Can you use kelvin_to_celsius(0) from units.h instead?

> +               *val2 = ret / 1000;
> +
> +               return IIO_VAL_FRACTIONAL;

...

> +#define LTC2497_T_CHAN {                                                                       \

It's better to locate { on the new line.

> +       .type = IIO_TEMP,                                                                       \
> +       .channel = 0,                                                                           \
> +       .address = (LTC2497_ENABLE_TEMPERATURE_CONV),                                           \
> +       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),                                           \
> +       .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),       \
> +}

...

> +       LTC2497_CHANNELS,

Seems like a terminator, so add _MAX in the middle and remove the
trailing comma.

...


> +static const struct iio_chan_spec ltc2497core_channel_with_temperature[] = {
> +       LTC2497_CHANNELS,
> +       LTC2497_T_CHAN,

(Same as above may be applied to _T_CHAN, but I haven't seen the enum
to be sure)

>  };

...

>  struct ltc2497_chip_info {
> -       u32 resolution;
>         const char *name;
> +       u32 resolution;

Perhaps above deserves a separate change (with the `pahole` summary),
but I don't care as it's a little change here. Leave this to Jonathan
to decide.

> +       /*
> +        * Represents the datasheet constant from the temperature formula:
> +        * T_Kelvin = (DATAOUT * Vref) / temp_scale, where Vref is in Volts.
> +        *
> +        * To allow the driver to use Vref in millivolts for the calculation
> +        * and also to avoid floating points, this stored value represents the
> +        * datasheet constant scaled by 1000.
> +        */
> +       u32 temp_scale_mV;
> +       bool has_temp_channel;
>  };

-- 
With Best Regards,
Andy Shevchenko

[PATCH v2 4/4] iio: adc: ltc2497: reorder ltc2497core_driverdata members to remove hole

[Yusuf Alper Bilgin]

Reorder struct members from largest to smallest to eliminate a 7-byte
hole identified by the pahole tool, making the layout memory-optimal.

Signed-off-by: Yusuf Alper Bilgin <y.alperbilgin@gmail.com>
---
 drivers/iio/adc/ltc2497.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ltc2497.h b/drivers/iio/adc/ltc2497.h
index 7f53bf8b8469d2371bb7ae64ce90a61beadba9ba..578f55efc5c400980fe8bbd2b220aafb222d6f33 100644
--- a/drivers/iio/adc/ltc2497.h
+++ b/drivers/iio/adc/ltc2497.h
@@ -27,12 +27,12 @@ struct ltc2497_chip_info {
 struct ltc2497core_driverdata {
 	struct regulator *ref;
 	ktime_t	time_prev;
-	/* lock to protect against multiple access to the device */
-	struct mutex lock;
 	const struct ltc2497_chip_info	*chip_info;
-	u8 addr_prev;
 	int (*result_and_measure)(struct ltc2497core_driverdata *ddata,
 				  u8 address, int *val);
+	/* lock to protect against multiple access to the device */
+	struct mutex lock;
+	u8 addr_prev;
 };
 
 int ltc2497core_probe(struct device *dev, struct iio_dev *indio_dev);

-- 
2.43.0

Re: [PATCH v2 4/4] iio: adc: ltc2497: reorder ltc2497core_driverdata members to remove hole

[Andy Shevchenko]

On Wed, Aug 13, 2025 at 6:54 PM Yusuf Alper Bilgin
<y.alperbilgin@gmail.com> wrote:
>
> Reorder struct members from largest to smallest to eliminate a 7-byte
> hole identified by the pahole tool, making the layout memory-optimal.

`pahole`

...

Cool, have you also checked the generated code with bloat-o-meter,
i.e. does the new object file is bigger/smaller/the same size as the
old one?

And make this patch with the one member shuffling from the previous one.


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 0/4] Add LTC2495 support

[Andy Shevchenko]

On Wed, Aug 13, 2025 at 6:54 PM Yusuf Alper Bilgin
<y.alperbilgin@gmail.com> wrote:
>
> Hi All,
>
> This is the v2 of the patch series to add support for the LTC2495 ADC to
> the ltc2497 driver and to enable the internal temperature channel for
> the LTC2495 and LTC2499.
>
> Many thanks to Andy Shevchenko and Krzysztof Kozlowski for their
> detailed and helpful reviews on v1. I believe I've addressed all
> feedbacks in this version.

You're welcome!

>       iio: adc: ltc2497: add support for LTC2495

I'm fine with this patch...

>       iio: adc: ltc2497: add temperature sensor support
>       iio: adc: ltc2497: reorder ltc2497core_driverdata members to remove hole

...but these two need a bit of work, I hope the next version will be final.

-- 
With Best Regards,
Andy Shevchenko