[PATCH v2 0/3] iio: adc: qcom-pm8xxx-xoadc: add support for reading channel labels from DT

[PATCH v2 0/3] iio: adc: qcom-pm8xxx-xoadc: add support for reading channel labels from DT

[Antony Kurniawan Soemardi]

This series adds support for reading channel labels from the device tree
in the Qualcomm PM8xxx XOADC driver, along with the corresponding DT
updates for the PM8921 PMIC. Redundant error logging in pm8xxx_read_raw
is also removed, as returning -EINVAL is sufficient when the channel is
not found.

Tested on Sony Xperia SP (PM8921):
> cat /sys/bus/iio/devices/iio\:device0/in_voltage7_label
usb_vbus
> cat /sys/bus/iio/devices/iio\:device0/in_temp12_label
ref_muxoff
> sensors
iio_hwmon-isa-0000
Adapter: ISA adapter
vbat:        267.86 V
dcin:          4.82 kV
...
chg_temp:    +1071.4°C

Note: the sensor readings above are incorrect due to pending calibration
fixes are not included in this series. This patch only addresses label
visibility. The values are expected to be wrong until the calibration
fixes lands separately.

Signed-off-by: Antony Kurniawan Soemardi <linux@smankusors.com>
---
Changes in v2:
- Remove redundant error logging in pm8xxx_read_raw, since -EINVAL is
  sufficient to report failures.
- Reword the uncommon Tested-by commit tag to freeform text
- Link to v1: https://lore.kernel.org/r/20260326-pm8xxx-xoadc-label-v1-0-027805dad4db@smankusors.com

Changes since original patch:
- The label is now read from the platform description (device tree)
  instead of the internal datasheet name.
- Link to original patch:
  https://lore.kernel.org/all/20251028-pm8xxx-xoadc-fix-v1-1-b000e1036e41@smankusors.com/

---
Antony Kurniawan Soemardi (3):
      ARM: dts: qcom: pm8921: add labels for ADC channels
      iio: adc: qcom-pm8xxx-xoadc: remove redundant error logging in pm8xxx_read_raw
      iio: adc: qcom-pm8xxx-xoadc: add support for reading channel labels

 arch/arm/boot/dts/qcom/pm8921.dtsi  | 12 ++++++++++++
 drivers/iio/adc/qcom-pm8xxx-xoadc.c | 34 +++++++++++++++++++++-------------
 2 files changed, 33 insertions(+), 13 deletions(-)
---
base-commit: 5619b098e2fbf3a23bf13d91897056a1fe238c6d
change-id: 20260321-pm8xxx-xoadc-label-47afdf7f06a9

Best regards,
--
Antony Kurniawan Soemardi <linux@smankusors.com>

[PATCH v2 1/3] ARM: dts: qcom: pm8921: add labels for ADC channels

[Antony Kurniawan Soemardi]

Add label properties to all XOADC ADC channel nodes in the PM8921 PMIC
device tree. This allows userspace and drivers to identify channels by
name rather than relying on datasheet name.

Acked-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Antony Kurniawan Soemardi <linux@smankusors.com>
---
 arch/arm/boot/dts/qcom/pm8921.dtsi | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm/boot/dts/qcom/pm8921.dtsi b/arch/arm/boot/dts/qcom/pm8921.dtsi
index 535cb6a2543f69bc30abc89bff4e14a19147ce38..15246f4bd2672ccd4fc3359b66541d53d4da88b4 100644
--- a/arch/arm/boot/dts/qcom/pm8921.dtsi
+++ b/arch/arm/boot/dts/qcom/pm8921.dtsi
@@ -75,50 +75,62 @@ pm8921_xoadc: xoadc@197 {
 
 			vcoin: adc-channel@0 {
 				reg = <0x00 0x00>;
+				label = "vcoin";
 			};
 
 			vbat: adc-channel@1 {
 				reg = <0x00 0x01>;
+				label = "vbat";
 			};
 
 			dcin: adc-channel@2 {
 				reg = <0x00 0x02>;
+				label = "dcin";
 			};
 
 			vph_pwr: adc-channel@4 {
 				reg = <0x00 0x04>;
+				label = "vph_pwr";
 			};
 
 			batt_therm: adc-channel@8 {
 				reg = <0x00 0x08>;
+				label = "batt_therm";
 			};
 
 			batt_id: adc-channel@9 {
 				reg = <0x00 0x09>;
+				label = "batt_id";
 			};
 
 			usb_vbus: adc-channel@a {
 				reg = <0x00 0x0a>;
+				label = "usb_vbus";
 			};
 
 			die_temp: adc-channel@b {
 				reg = <0x00 0x0b>;
+				label = "die_temp";
 			};
 
 			ref_625mv: adc-channel@c {
 				reg = <0x00 0x0c>;
+				label = "ref_625mv";
 			};
 
 			ref_1250mv: adc-channel@d {
 				reg = <0x00 0x0d>;
+				label = "ref_1250mv";
 			};
 
 			chg_temp: adc-channel@e {
 				reg = <0x00 0x0e>;
+				label = "chg_temp";
 			};
 
 			ref_muxoff: adc-channel@f {
 				reg = <0x00 0x0f>;
+				label = "ref_muxoff";
 			};
 		};
 	};

-- 
2.34.1

Re: [PATCH v2 1/3] ARM: dts: qcom: pm8921: add labels for ADC channels

[Dmitry Baryshkov]

On Fri, Apr 03, 2026 at 09:23:14AM +0000, Antony Kurniawan Soemardi wrote:
> Add label properties to all XOADC ADC channel nodes in the PM8921 PMIC
> device tree. This allows userspace and drivers to identify channels by
> name rather than relying on datasheet name.
> 
> Acked-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
> Signed-off-by: Antony Kurniawan Soemardi <linux@smankusors.com>
> ---
>  arch/arm/boot/dts/qcom/pm8921.dtsi | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry

[PATCH v2 2/3] iio: adc: qcom-pm8xxx-xoadc: remove redundant error logging in pm8xxx_read_raw

[Antony Kurniawan Soemardi]

Remove dev_err() for missing channels and rely on -EINVAL to report
failures, reducing unnecessary log noise.

Signed-off-by: Antony Kurniawan Soemardi <linux@smankusors.com>
---
 drivers/iio/adc/qcom-pm8xxx-xoadc.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/adc/qcom-pm8xxx-xoadc.c b/drivers/iio/adc/qcom-pm8xxx-xoadc.c
index 31f88cf7f7f18297132d152648b312c0fb60608e..d63af84bf44776c9c7106a43473b1678496247cb 100644
--- a/drivers/iio/adc/qcom-pm8xxx-xoadc.c
+++ b/drivers/iio/adc/qcom-pm8xxx-xoadc.c
@@ -657,11 +657,8 @@ static int pm8xxx_read_raw(struct iio_dev *indio_dev,
 	switch (mask) {
 	case IIO_CHAN_INFO_PROCESSED:
 		ch = pm8xxx_get_channel(adc, chan->address);
-		if (!ch) {
-			dev_err(adc->dev, "no such channel %lu\n",
-				chan->address);
+		if (!ch)
 			return -EINVAL;
-		}
 		ret = pm8xxx_read_channel(adc, ch, &adc_code);
 		if (ret)
 			return ret;
@@ -677,11 +674,8 @@ static int pm8xxx_read_raw(struct iio_dev *indio_dev,
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_RAW:
 		ch = pm8xxx_get_channel(adc, chan->address);
-		if (!ch) {
-			dev_err(adc->dev, "no such channel %lu\n",
-				chan->address);
+		if (!ch)
 			return -EINVAL;
-		}
 		ret = pm8xxx_read_channel(adc, ch, &adc_code);
 		if (ret)
 			return ret;

-- 
2.34.1

Re: [PATCH v2 2/3] iio: adc: qcom-pm8xxx-xoadc: remove redundant error logging in pm8xxx_read_raw

[Dmitry Baryshkov]

On Fri, Apr 03, 2026 at 09:23:18AM +0000, Antony Kurniawan Soemardi wrote:
> Remove dev_err() for missing channels and rely on -EINVAL to report
> failures, reducing unnecessary log noise.


Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

Does it also prevent users from spamming the dmesg?

> 
> Signed-off-by: Antony Kurniawan Soemardi <linux@smankusors.com>
> ---
>  drivers/iio/adc/qcom-pm8xxx-xoadc.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 

-- 
With best wishes
Dmitry

Re: [PATCH v2 2/3] iio: adc: qcom-pm8xxx-xoadc: remove redundant error logging in pm8xxx_read_raw

[Antony Kurniawan Soemardi]

On 4/4/2026 4:54 AM, Dmitry Baryshkov wrote:
> Does it also prevent users from spamming the dmesg?

It should be for no such channel case. The only remaining error logs
from pm8xxx_read_raw are timeout errors, which I don’t think would
result in immediate spamming. Or should we remove the dev_err (at
pm8xxx_read_channel_rsv) on timeout errors too?

-- 
Thanks,
Antony K. S.

Re: [PATCH v2 2/3] iio: adc: qcom-pm8xxx-xoadc: remove redundant error logging in pm8xxx_read_raw

[Andy Shevchenko]

On Sat, Apr 04, 2026 at 03:26:32AM +0000, Antony Kurniawan Soemardi wrote:
> On 4/4/2026 4:54 AM, Dmitry Baryshkov wrote:
> > Does it also prevent users from spamming the dmesg?
> 
> It should be for no such channel case. The only remaining error logs
> from pm8xxx_read_raw are timeout errors, which I don’t think would
> result in immediate spamming. Or should we remove the dev_err (at
> pm8xxx_read_channel_rsv) on timeout errors too?

Does the user get -ETIMEDOUT? If so, yes, message may be removed.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 2/3] iio: adc: qcom-pm8xxx-xoadc: remove redundant error logging in pm8xxx_read_raw

[Andy Shevchenko]

On Sat, Apr 04, 2026 at 12:54:29AM +0300, Dmitry Baryshkov wrote:
> On Fri, Apr 03, 2026 at 09:23:18AM +0000, Antony Kurniawan Soemardi wrote:
> > Remove dev_err() for missing channels and rely on -EINVAL to report
> > failures, reducing unnecessary log noise.
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
> 
> Does it also prevent users from spamming the dmesg?

That was and IIUC is the main point of the patch.

-- 
With Best Regards,
Andy Shevchenko

[PATCH v2 3/3] iio: adc: qcom-pm8xxx-xoadc: add support for reading channel labels

[Antony Kurniawan Soemardi]

Implement the .read_label callback to allow userspace to identify ADC
channels via the "label" property in the device tree. The name field in
pm8xxx_chan_info is renamed to label to better reflect its purpose. If
no label is provided in the device tree, it defaults to the hardware
datasheet name.

The change has been tested on Sony Xperia SP (PM8921).

Signed-off-by: Antony Kurniawan Soemardi <linux@smankusors.com>
---
 drivers/iio/adc/qcom-pm8xxx-xoadc.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/qcom-pm8xxx-xoadc.c b/drivers/iio/adc/qcom-pm8xxx-xoadc.c
index d63af84bf44776c9c7106a43473b1678496247cb..f473c5e0c5a217bb4a3773177b6e02f0603d7de6 100644
--- a/drivers/iio/adc/qcom-pm8xxx-xoadc.c
+++ b/drivers/iio/adc/qcom-pm8xxx-xoadc.c
@@ -369,7 +369,7 @@ static const struct xoadc_channel pm8921_xoadc_channels[] = {
 
 /**
  * struct pm8xxx_chan_info - ADC channel information
- * @name: name of this channel
+ * @label: label of this channel from device tree (defaults to datasheet name if not specified)
  * @hwchan: pointer to hardware channel information (muxing & scaling settings)
  * @calibration: whether to use absolute or ratiometric calibration
  * @decimation: 0,1,2,3
@@ -377,7 +377,7 @@ static const struct xoadc_channel pm8921_xoadc_channels[] = {
  * calibration: 0, 1, 2, 4, 5.
  */
 struct pm8xxx_chan_info {
-	const char *name;
+	const char *label;
 	const struct xoadc_channel *hwchan;
 	enum vadc_calibration calibration;
 	u8 decimation:2;
@@ -446,7 +446,7 @@ static int pm8xxx_read_channel_rsv(struct pm8xxx_xoadc *adc,
 	u8 lsb, msb;
 
 	dev_dbg(adc->dev, "read channel \"%s\", amux %d, prescale/mux: %d, rsv %d\n",
-		ch->name, ch->hwchan->amux_channel, ch->hwchan->pre_scale_mux, rsv);
+		ch->label, ch->hwchan->amux_channel, ch->hwchan->pre_scale_mux, rsv);
 
 	mutex_lock(&adc->lock);
 
@@ -719,8 +719,20 @@ static int pm8xxx_fwnode_xlate(struct iio_dev *indio_dev,
 	return -EINVAL;
 }
 
+static int pm8xxx_read_label(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, char *label)
+{
+	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
+	struct pm8xxx_chan_info *ch = pm8xxx_get_channel(adc, chan->address);
+
+	if (!ch)
+		return -EINVAL;
+	return sysfs_emit(label, "%s\n", ch->label);
+}
+
 static const struct iio_info pm8xxx_xoadc_info = {
 	.fwnode_xlate = pm8xxx_fwnode_xlate,
+	.read_label = pm8xxx_read_label,
 	.read_raw = pm8xxx_read_raw,
 };
 
@@ -764,7 +776,9 @@ static int pm8xxx_xoadc_parse_channel(struct device *dev,
 			pre_scale_mux, amux_channel);
 		return -EINVAL;
 	}
-	ch->name = name;
+	ret = fwnode_property_read_string(fwnode, "label", &ch->label);
+	if (ret)
+		ch->label = hwchan->datasheet_name;
 	ch->hwchan = hwchan;
 	/* Everyone seems to use absolute calibration except in special cases */
 	ch->calibration = VADC_CALIB_ABSOLUTE;
@@ -806,7 +820,7 @@ static int pm8xxx_xoadc_parse_channel(struct device *dev,
 
 	dev_dbg(dev,
 		"channel [PRESCALE/MUX: %02x AMUX: %02x] \"%s\" ref voltage: %d, decimation %d prescale %d/%d, scale function %d\n",
-		hwchan->pre_scale_mux, hwchan->amux_channel, ch->name,
+		hwchan->pre_scale_mux, hwchan->amux_channel, ch->label,
 		ch->amux_ip_rsv, ch->decimation, hwchan->prescale.numerator,
 		hwchan->prescale.denominator, hwchan->scale_fn_type);
 

-- 
2.34.1

Re: [PATCH v2 3/3] iio: adc: qcom-pm8xxx-xoadc: add support for reading channel labels

[Dmitry Baryshkov]

On Fri, Apr 03, 2026 at 09:23:21AM +0000, Antony Kurniawan Soemardi wrote:
> Implement the .read_label callback to allow userspace to identify ADC
> channels via the "label" property in the device tree. The name field in
> pm8xxx_chan_info is renamed to label to better reflect its purpose. If
> no label is provided in the device tree, it defaults to the hardware
> datasheet name.
> 
> The change has been tested on Sony Xperia SP (PM8921).
> 
> Signed-off-by: Antony Kurniawan Soemardi <linux@smankusors.com>
> ---
>  drivers/iio/adc/qcom-pm8xxx-xoadc.c | 24 +++++++++++++++++++-----
>  1 file changed, 19 insertions(+), 5 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry

Re: [PATCH v2 3/3] iio: adc: qcom-pm8xxx-xoadc: add support for reading channel labels

[Andy Shevchenko]

On Fri, Apr 03, 2026 at 09:23:21AM +0000, Antony Kurniawan Soemardi wrote:
> Implement the .read_label callback to allow userspace to identify ADC
> channels via the "label" property in the device tree. The name field in
> pm8xxx_chan_info is renamed to label to better reflect its purpose. If
> no label is provided in the device tree, it defaults to the hardware
> datasheet name.
> 
> The change has been tested on Sony Xperia SP (PM8921).

...

> +	ret = fwnode_property_read_string(fwnode, "label", &ch->label);
> +	if (ret)
> +		ch->label = hwchan->datasheet_name;

Branch is not needed.

	ch->label = hwchan->datasheet_name;
	fwnode_property_read_string(fwnode, "label", &ch->label);

will have the same effect. But if you want to handle errors, you may do

	if (fwnode_property_present(...)) {
		ret = fwnode_property_read_string(...);
		if (ret)
			return ret;
	} else {
		...assign default...
	}


-- 
With Best Regards,
Andy Shevchenko