Re: [PATCH v3 RFC v3] dt-bindings: iio: adc: add ad7816/7/8 digital temperature sensor / ADC
From: Taha Narimani
Date: Sun May 31 2026 - 13:05:21 EST
Hi Jonathan,
Thank you for your patience and the detailed review of v2. I apologize
for rushing the v3 submission and omitting the changelog. I am still
familiarizing myself with the kernel mailing list etiquette, and I
will certainly slow down and allow at least a week for future patch
revisions to ensure proper discussion time.
As you recommended, I took a step back and thoroughly read the
AD7816/7/8 datasheets. That was a great learning point—it helped me
realize that the AD7816 (8-pin) completely lacks a BUSY pin, which the
current staging driver incorrectly requests unconditionally. I also
mapped out the missing power supplies and OTI interrupts based on the
datasheet specifications to make the binding complete.
Here is the requested changelog for this version:
Changes in v3:
- Updated the patch title and marked it explicitly as an RFC, noting
the driver's staging status.
- Added `spi-max-frequency` with a maximum limit of 12.5MHz based on
the datasheet.
- Added `vdd-supply` and `vref-supply` properties (making vref-supply
optional where an internal reference exists).
- Implemented conditional schema logic: restricted `busy-gpios`
exclusively to the `adi,ad7817` variant and disallowed `vref-supply`
for `adi,ad7818`.
- Documented the `interrupts` property for the OTI pin (Active low) to
resolve the validation error in the v2 example.
- Modified the example block to use `adi,ad7817` to correctly align
with the `busy-gpios` requirement.
Best regards,
Taha Narimani
On Sun, May 31, 2026 at 6:12 PM Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
>
> On Sat, 30 May 2026 16:59:15 +0000
> Taha Narimani <tahanarimani3443@xxxxxxxxx> wrote:
>
> > Document the Analog Devices AD7816, AD7817, and AD7818 digital
> > temperature sensor and ADC bindings in YAML format.
> >
> > Please note that the driver for this device is currently in drivers/staging.
> > This patch is sent as an RFC to clean up and standardize the device tree
> > bindings prior to any major driver refactoring.
> >
> > While reviewing the AD7816/7/8 datasheet to correctly document the properties,
> > it was noted that the current staging driver attempts to request a 'busy' GPIO
> > for both AD7816 and AD7817. However, the AD7816 is an 8-pin device and does
> > not possess a BUSY pin (only the 16-pin AD7817 has it). Therefore, in this
> > binding, busy-gpios is strictly limited to adi,ad7817.
> >
> > This resolves the checkpatch.pl warnings regarding undocumented DT
> > compatible strings.
> >
> > Signed-off-by: Taha Narimani <tahanarimani3443@xxxxxxxxx>
> > ---
> Hi Taha,
>
> There should be a change log here. Please reply to this thread with that for
> this version.
>
> Also, slow down. For any patch allow at least 24 hours unless a maintainer
> specifically requests it faster. For most stuff a week. That way any ongoing
> discussion can finish and additional reviewers have time to take a look.
>
>
> > .../bindings/iio/adc/adi,ad7816.yaml | 105 ++++++++++++++++++
> > 1 file changed, 105 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml
> > new file mode 100644
> > index 0000000..48563e4
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7816.yaml
> > @@ -0,0 +1,105 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/iio/adc/adi,ad7816.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Analog Devices AD7816/7/8 digital temperature sensor / ADC
> > +
> > +maintainers:
> > + - Taha Narimani <tahanarimani3443@xxxxxxxxx>
> > +
> > +description: |
> > + Analog Devices AD7816, AD7817, and AD7818 10-Bit general purpose ADC and
> > + temperature sensor. The device communicates via an SPI interface.
> > +
> > +properties:
> > + compatible:
> > + enum:
> > + - adi,ad7816
> > + - adi,ad7817
> > + - adi,ad7818
> > +
> > + reg:
> > + maxItems: 1
> > +
> > + spi-max-frequency:
> > + maximum: 12500000
> > +
> > + vdd-supply:
> > + description: Main power supply.
> > +
> > + vref-supply:
> > + description: |
> > + Optional external reference voltage supply. If not provided, the
> > + internal reference is used. Applicable for AD7816 and AD7817.
> > +
> > + rdwr-gpios:
> > + maxItems: 1
> > + description: GPIO connected to the RD/WR pin.
> > +
> > + convert-gpios:
> > + maxItems: 1
> > + description: GPIO connected to the CONVST (Convert Start) pin.
> > +
> > + busy-gpios:
> > + maxItems: 1
> > + description: GPIO connected to the BUSY pin. Only applicable for AD7817.
> > +
> > + interrupts:
> > + maxItems: 1
> > + description: OTI (Over Temperature Indicator) interrupt. Active low.
> > +
> > +required:
> > + - compatible
> > + - reg
> > + - vdd-supply
> > + - rdwr-gpios
> > + - convert-gpios
> > +
> > +allOf:
> > + - $ref: /schemas/spi/spi-peripheral-props.yaml#
> > + - if:
> > + properties:
> > + compatible:
> > + contains:
> > + const: adi,ad7817
> > + then:
> > + required:
> > + - busy-gpios
> > + else:
> > + properties:
> > + busy-gpios: false
> > + - if:
> > + properties:
> > + compatible:
> > + contains:
> > + const: adi,ad7818
> > + then:
> > + properties:
> > + vref-supply: false
> > +
> > +unevaluatedProperties: false
> > +
> > +examples:
> > + - |
> > + #include <dt-bindings/gpio/gpio.h>
> > + #include <dt-bindings/interrupt-controller/irq.h>
> > +
> > + spi {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + adc@0 {
> > + compatible = "adi,ad7817";
> > + reg = <0>;
> > + spi-max-frequency = <1000000>;
> > + vdd-supply = <&vcc>;
> > + vref-supply = <&vref>;
> > + rdwr-gpios = <&gpio 5 GPIO_ACTIVE_HIGH>;
> > + convert-gpios = <&gpio 6 GPIO_ACTIVE_HIGH>;
> > + busy-gpios = <&gpio 7 GPIO_ACTIVE_HIGH>;
> > + interrupts = <20 IRQ_TYPE_LEVEL_LOW>;
> > + interrupt-parent = <&gpio>;
> > + };
> > + };
>