> From: Jonathan Cameron <jic23@xxxxxxxxxxxxxxxxxxxxx> > Sent: Thursday, December 30, 2021 4:44 PM > To: Sa, Nuno <Nuno.Sa@xxxxxxxxxx>; devicetree@xxxxxxxxxxxxxxx > Cc: Rob Herring <robh@xxxxxxxxxx>; linux-iio@xxxxxxxxxxxxxxx; Lars- > Peter Clausen <lars@xxxxxxxxxx>; Hennerich, Michael > <Michael.Hennerich@xxxxxxxxxx> > Subject: Re: [PATCH 3/3] dt-bindings: iio: Add ltc2688 documentation > > [External] > > On Fri, 17 Dec 2021 09:09:30 +0000 > "Sa, Nuno" <Nuno.Sa@xxxxxxxxxx> wrote: > > > > From: Jonathan Cameron <jic23@xxxxxxxxxxxxxxxxxxxxx> > > > Sent: Thursday, December 16, 2021 2:33 PM > > > To: Rob Herring <robh@xxxxxxxxxx> > > > Cc: Sa, Nuno <Nuno.Sa@xxxxxxxxxx>; linux-iio@xxxxxxxxxxxxxxx; > > > devicetree@xxxxxxxxxxxxxxx; Lars-Peter Clausen > <lars@xxxxxxxxxx>; > > > Hennerich, Michael <Michael.Hennerich@xxxxxxxxxx> > > > Subject: Re: [PATCH 3/3] dt-bindings: iio: Add ltc2688 > documentation > > > > > > > > > On Wed, 15 Dec 2021 15:30:37 -0600 > > > Rob Herring <robh@xxxxxxxxxx> wrote: > > > > > > > On Tue, Dec 14, 2021 at 05:56:08PM +0100, Nuno Sá wrote: > > > > > Document the LTC2688 devicetree properties. > > > > > > > > > > Signed-off-by: Nuno Sá <nuno.sa@xxxxxxxxxx> > > > > > --- > > > > > .../bindings/iio/dac/adi,ltc2688.yaml | 146 > > > ++++++++++++++++++ > > > > > MAINTAINERS | 1 + > > > > > 2 files changed, 147 insertions(+) > > > > > create mode 100644 > > > Documentation/devicetree/bindings/iio/dac/adi,ltc2688.yaml > > > > > > > > > > diff --git > > > a/Documentation/devicetree/bindings/iio/dac/adi,ltc2688.yaml > > > b/Documentation/devicetree/bindings/iio/dac/adi,ltc2688.yaml > > > > > new file mode 100644 > > > > > index 000000000000..7919cd8ec7c9 > > > > > --- /dev/null > > > > > +++ > > > b/Documentation/devicetree/bindings/iio/dac/adi,ltc2688.yaml > > > > > @@ -0,0 +1,146 @@ > > > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > > > > > +%YAML 1.2 > > > > > +--- > > > > > +$id: > > > > https://urldefense.com/v3/__http://devicetree.org/schemas/iio/dac/ > > > > adi,ltc2688.yaml*__;Iw!!A3Ni8CS0y2Y!rHThZYvGYZfm2zOTRFsr1xH61Bf > > > mq371ojtDKEdpTSeC7lCU_dS7CnRBJvPcEQ$ > > > > > +$schema: > > > https://urldefense.com/v3/__http://devicetree.org/meta- > > > > schemas/core.yaml*__;Iw!!A3Ni8CS0y2Y!rHThZYvGYZfm2zOTRFsr1xH > > > 61Bfmq371ojtDKEdpTSeC7lCU_dS7CnSFhKxW0w$ > > > > > + > > > > > +title: Analog Devices LTC2688 DAC > > > > > + > > > > > +maintainers: > > > > > + - Nuno Sá <nuno.sa@xxxxxxxxxx> > > > > > + > > > > > +description: | > > > > > + Analog Devices LTC2688 16 channel, 16 bit, +-15V DAC > > > > > + https://www.analog.com/media/en/technical- > > > documentation/data-sheets/ltc2688.pdf > > > > > + > > > > > +properties: > > > > > + compatible: > > > > > + enum: > > > > > + - adi,ltc2688 > > > > > + > > > > > + reg: > > > > > + maxItems: 1 > > > > > + > > > > > + vcc-supply: > > > > > + description: Analog Supply Voltage Input. > > > > > + > > > > > + iovcc-supply: > > > > > + description: Digital Input/Output Supply Voltage. > > > > > + > > > > > + vref-supply: > > > > > + description: > > > > > + Reference Input/Output. The voltage at the REF pin sets > the > > > full-scale > > > > > + range of all channels. By default, the internal reference is > > > routed to > > > > > + this pin. > > > > > + > > > > > + reset-gpios: > > > > > + description: > > > > > + If specified, it will be asserted during driver probe. As the > line is > > > > > + active low, it should be marked GPIO_ACTIVE_LOW. > > > > > + maxItems: 1 > > > > > + > > > > > + clocks: > > > > > + minItems: 1 > > > > > + maxItems: 3 > > > > > + > > > > > + clock-names: > > > > > + minItems: 1 > > > > > + maxItems: 3 > > > > > + items: > > > > > + enum: [TGP1, TGP2, TGP3] > > > > > > > > pattern: '^TGP[1-3]$' > > > > > > > > > + > > > > > + '#address-cells': > > > > > + const: 1 > > > > > + > > > > > + '#size-cells': > > > > > + const: 0 > > > > > + > > > > > +patternProperties: > > > > > + "^channel@([0-9]|1[0-5])$": > > > > > + type: object > > > > > + > > > > > + properties: > > > > > + reg: > > > > > + description: The channel number representing the DAC > > > output channel. > > > > > + maximum: 15 > > > > > + > > > > > + adi,toggle-mode: > > > > > + description: > > > > > + Set the channel as a toggle enabled channel. Toggle > > > operation enables > > > > > + fast switching of a DAC output between two different > DAC > > > codes without > > > > > + any SPI transaction. It will result in a different ABI for the > > > > > + channel. > > > > > + type: boolean > > > > > + > > > > > + adi,output-range-millivolt: > > > > > > > > Not one of the defined units. Use '-microvolt' > > > > > > > > + description: > > > > > + Specify the channel output full scale range. Allowed > values > > > are > > > > > + <0 5000> > > > > > + <0 10000> > > > > > + <-5000 5000> > > > > > + <-10000 10000> > > > > > + <-15000 15000> > > > > > > > > Looks like constraints. > > > > > > > > items: > > > > - enum: [ -15000, -10000, -5000, 0 ] > > > > - enum: [ 5000, 10000, 15000 ] > > > > > > > > though that will need to all be x1000. > > > > > > also should be constrained to allowed combinations which probably > > > means a oneOf construct. > > > > > > > Exactly. AFICT, with Rob's suggestion things like <-15000 5000> would > > be validated but not really possible and the driver does not allow it. I > did > > tried some stuff before sending this simplified form (constrains in > description): > > > > ... > > oneOf: > > - items: > > - const: 0 > > - enum: [5000, 10000] > > - items: > > - const: -5000 > > - const: 5000 > > ... > > > > Whiles things worked for <0 5000> and <0 10000>, they failed for <(- > 5000) 5000>: > > > > " > > > next/Documentation/devicetree/bindings/iio/dac/adi,ltc2688.example > .dt.y > > aml: ltc2688@0: channel@1:adi,output-range-millivolt: 'oneOf' > > conditional failed, one must be fixed: > > 0 was expected > > -5000 was expected > > From schema: /home/nsa/work/linux-adi- > > next/Documentation/devicetree/bindings/iio/dac/adi,ltc2688.yam" > > > > Trying this combination <0 (-5000)> led to: > > > > " > > > next/Documentation/devicetree/bindings/iio/dac/adi,ltc2688.example > .dt.y > > aml: ltc2688@0: channel@1:adi,output-range-microvolt: 'oneOf' > > conditional failed, one must be fixed: > > -5000 was expected > > 4294962296 is not one of [5000, 10000] > > From schema: /home/nsa/work/linux-adi- > > next/Documentation/devicetree/bindings/iio/dac/adi,ltc2688.yaml > > " > > > > it makes me feel that something is going on with signed/unsigned > > comparisons. But I might be completely off with this approach :) > > I'll go with huh... > > Documentation/devicetree/bindings/iio/dac/adi,ad3552r.yaml > > and other places have pretty much the same construct though > examples > don't actually use it. > > I have some vague recollection of a previous discussion about > negatives > and that Rob had some plan to make them work long term. In the > meantime > we just avoid them in the examples. > > Rob, is my memory deceiving me? > Rob, any input on this? Should I just not add the property to the examples for now? - Nuno Sá
