On 01/27, David Lechner wrote:
> On 1/27/25 9:11 AM, Jonathan Santos wrote:
> > Add a new trigger-sources property to enable synchronization across
> > multiple devices. This property references the main device (or
> > trigger provider) responsible for generating the pulse to drive the
> > SYNC_IN of all devices in the setup.
> >
> > In addition to GPIO synchronization, The AD7768-1 also supports
> > synchronization over SPI, which use is recommended when the GPIO
> > cannot provide a pulse synchronous with the base MCLK signal. It
> > consists of looping back the SYNC_OUT to the SYNC_IN pin and send
> > a command via SPI to trigger the synchronization.
> >
> > SPI-based synchronization is enabled in the absence of adi,sync-in-gpios
> > property. Since adi,sync-in-gpios is not long the only method, remove it
> > from required properties.
> >
> > While at it, add description to the interrupt property.
> >
> > Signed-off-by: Jonathan Santos <Jonathan.Santos@xxxxxxxxxx>
> > ---
> > v2 Changes:
> > * Patch added as replacement for adi,sync-in-spi patch.
> > * addressed the request for a description to interrupts property.
> > ---
> > .../bindings/iio/adc/adi,ad7768-1.yaml | 22 +++++++++++++++++--
> > 1 file changed, 20 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> > index 3ce59d4d065f..3e119cf1754b 100644
> > --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> > @@ -26,7 +26,17 @@ properties:
> > clock-names:
> > const: mclk
> >
> > + trigger-sources:
> > + description:
> > + References the main device responsible for synchronization. In a single
> > + device setup, reference the own node.
> > + maxItems: 1
>
> We probably actually need 2 here. One for /SYNC_IN and one for a GPIO3 pin
> acting as the /START signal.
>
> > +
> > interrupts:
> > + description:
> > + Specifies the interrupt line associated with the ADC. This refers
> > + to the DRDY (Data Ready) pin, which signals when conversion results are
> > + available.
> > maxItems: 1
> >
> > '#address-cells':
> > @@ -46,6 +56,8 @@ properties:
> > sampling. A pulse is always required if the configuration is changed
> > in any way, for example if the filter decimation rate changes.
> > As the line is active low, it should be marked GPIO_ACTIVE_LOW.
> > + In the absence of this property, Synchronization over SPI will be
> > + enabled.
>
> Isn't /SYNC_OUT connected to /SYNC_IN required for synchronization over SPI?
>
> If yes, instead of adding this text, I would make the binding have:
>
Yes, but the synchronization over SPI is enabled in the absence of the GPIO.
The trigger-sources property would indicate if the sync provider is the
own device or not. As i said below, maybe i misunderstood.
> oneOf:
> - required:
> - trigger-sources
> - required:
> - adi,sync-in-gpios
>
Wouldn't be simpler to consider the absence of sync-in-gpio? this way we
have less changes in the ABI.
> >
> > reset-gpios:
> > maxItems: 1
> > @@ -57,6 +69,9 @@ properties:
> > "#io-channel-cells":
> > const: 1
> >
> > + "#trigger-source-cells":
> > + const: 0
> > +
> > required:
> > - compatible
> > - reg
> > @@ -65,7 +80,8 @@ required:
> > - vref-supply
> > - spi-cpol
> > - spi-cpha
> > - - adi,sync-in-gpios
> > + - trigger-sources
> > + - #trigger-source-cells
> >
> > patternProperties:
> > "^channel@([0-9]|1[0-5])$":
> > @@ -99,7 +115,7 @@ examples:
> > #address-cells = <1>;
> > #size-cells = <0>;
> >
> > - adc@0 {
> > + adc0: adc@0 {
> > compatible = "adi,ad7768-1";
> > reg = <0>;
> > spi-max-frequency = <2000000>;
> > @@ -109,6 +125,8 @@ examples:
> > interrupts = <25 IRQ_TYPE_EDGE_RISING>;
> > interrupt-parent = <&gpio>;
> > adi,sync-in-gpios = <&gpio 22 GPIO_ACTIVE_LOW>;
>
> Don't we need to drop adi,sync-in-gpios here? I don't think we would have two
> things connected to /SYNC_IN at the same time.
>
I guess i misunderstood the use of trigger-sources. I thought it would
indicate the trigger provider or main device. Like if it points to other
device we should use it to drive the SYNC_IN of all devices.
Then what happens if the trigger-sources points to other node? we would't be
able to driver the SYNC_IN in case of any configuration change?
> > + trigger-sources = <&adc0>;
> > + #trigger-source-cells = <0>;
> > reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
> > clocks = <&ad7768_mclk>;
> > clock-names = "mclk";
>
