Hi David, thank you for chiming in On Thu, Jun 12, 2025 at 10:03:37AM -0500, David Lechner wrote: > On 6/12/25 5:11 AM, Jorge Marques wrote: > > On Wed, Jun 11, 2025 at 06:18:18PM +0100, Jonathan Cameron wrote: > >> On Tue, 10 Jun 2025 09:34:35 +0200 > >> Jorge Marques <jorge.marques@xxxxxxxxxx> wrote: > >> > > ... > > >>> + trigger-sources: > >>> + minItems: 1 > >>> + maxItems: 2 > >>> + description: > >>> + Describes the output pin and event associated. > > trigger-sources would be an input pin connected to an external trigger. > For example, the CNV pin could be connected to a trigger-source > provider to trigger a conversion. But there aren't any other digital > inputs, so I don't know what the 2nd source would be here. > > As an example, see [1]. We could potentially use the same gpio > trigger-source for the conversion pin here. There is already > a similar binding for pwm triggers, so we could drop the separate > pwms binding as well an just have a single trigger-sources > property for the CNV pin that works for both gpio and pwm. > > [1]: https://lore.kernel.org/linux-iio/cover.1749569957.git.Jonathan.Santos@xxxxxxxxxx/ > Quick summary to familiarize myself with this part and driver. On ad7768-1: ad7768-1.SYNC_OUT is a digital output, ad7768-1.SYNC_IN input, and ad7768-1.GPIO3 (START) configured as input. ad7768-1.GPIO[0..3] are configurable GPIO, GPIO3 as START, or in PIN control mode, the input GPIO[3:0] sets the power mode and modulator freq (MODEx). On that thread: https://lore.kernel.org/linux-iio/8abca580f43cb31d7088d07a7414b5f7efe91ead.1749569957.git.Jonathan.Santos@xxxxxxxxxx/ exposes GPIO[0..3] through gpio_chip if gpio-controller in dt. https://lore.kernel.org/linux-iio/713fd786010c75858700efaec8bb285274e7057e.1749569957.git.Jonathan.Santos@xxxxxxxxxx/ trigger-sources-cells: the cell define the type of signal but *not* its origin, because {DRDY, SYNC_OUT, GPIO3(START)} are dedicated pins, *so there is no need to do so*. > >>> + > >>> + "#trigger-source-cells": > >>> + const: 2 > >>> + description: | > >>> + Output pins used as trigger source. > >>> + > >>> + Cell 0 defines the event: > >>> + * 0 = Data ready > >>> + * 1 = Min threshold > >>> + * 2 = Max threshold > >>> + * 3 = Either threshold > >>> + * 4 = CHOP control > >>> + * 5 = Device enable > >>> + * 6 = Device ready (only GP1) > >> > >> Hmm. I'm a bit dubious on why 'what the offload trigger is' > >> is a DT thing? Is that because the IP needs to comprehend > >> this? I guess only data ready is actually supported in > >> practice? > > > > A trigger can be connected to trigger something other than a spi > > offload, it is in the DT because it describes how the device is > > connected. When using spi offload, the trigger-source at the spi handle > > describes which gpio and event is routed to the offload trigger input. > > At the ADC node, trigger-source-cells describe the source gpio and event > > for the device driver. > > > > In practice, in this series, one gpio is Data ready, triggering offload > > when buffer enabled, and raw reads, when disabled. And the other is > > Either threshold, propagated as an IIO event. Fancy logic can be added > > to the driver in future patches to allow other combinations. > > > > It is also worth to mention that the trigger-source is duplicated for > > each node that uses it, as seen in the second dts example: > > > > &adc AD4052_TRIGGER_EVENT_DATA_READY AD4052_TRIGGER_PIN_GP1 > > > > Is repeated on both adc and spi node. > > That sounds wrong. This would only make sense if an output of the > ADC was wired back to itself. > The issue is the lack of way of describing to the driver the function of each gpio, when configurable. Perhaps it is better to use trigger-source-cells to only describe the topology at that node receiving the trigger, e.g. trigger-sources = <&adc AD4052_TRIGGER_PIN_GP0>; Below I continue the discussion. > > > > One last thing, on the driver, for v3, I should handle -ENOENT: > > > > ret = of_parse_phandle_with_args(np, "trigger-sources", > > "#trigger-source-cells", i, > > &trigger_sources); > > if (ret) > > return ret == -ENOENT ? 0 : ret; > > > > To assert only when present, since the nodes are not required. > > Or, in the driver, > > require AD4052_TRIGGER_PIN_GP0 if irq_get_byname finds gp0, and > > require AD4052_TRIGGER_PIN_GP1 if irq_get_byname finds gp1? > > (I would go with the first option). > >> > > ,,, > > >>> +examples: > >>> + - | > >>> + #include <dt-bindings/gpio/gpio.h> > >>> + #include <dt-bindings/interrupt-controller/irq.h> > >>> + #include <dt-bindings/iio/adc/adi,ad4052.h> > >>> + > >>> + spi { > >>> + #address-cells = <1>; > >>> + #size-cells = <0>; > >>> + > >>> + adc@0 { > >>> + compatible = "adi,ad4052"; > >>> + reg = <0>; > >>> + vdd-supply = <&vdd>; > >>> + vio-supply = <&vio>; > >>> + ref-supply = <&ref>; > >>> + spi-max-frequency = <83333333>; > >>> + > >>> + #trigger-source-cells = <2>; > >>> + trigger-sources = <&adc AD4052_TRIGGER_EVENT_EITHER_THRESH > >>> + AD4052_TRIGGER_PIN_GP0 > >>> + &adc AD4052_TRIGGER_EVENT_DATA_READY > >>> + AD4052_TRIGGER_PIN_GP1>; > > This doesn't make sense for the reason given above. These outputs > aren't wired back to inputs on the ADC. They are wired to interrupts > on the MCU, which is already described below. > Below. > >>> + interrupt-parent = <&gpio>; > >>> + interrupts = <0 0 IRQ_TYPE_EDGE_RISING>, > >>> + <0 1 IRQ_TYPE_EDGE_FALLING>; > >>> + interrupt-names = "gp0", "gp1"; > >>> + cnv-gpios = <&gpio 2 GPIO_ACTIVE_HIGH>; > >>> + }; > >>> + }; > >>> + - | > >>> + #include <dt-bindings/gpio/gpio.h> > >>> + #include <dt-bindings/interrupt-controller/irq.h> > >>> + #include <dt-bindings/iio/adc/adi,ad4052.h> > >>> + > >>> + rx_dma { > >>> + #dma-cells = <1>; > >>> + }; > >>> + > >>> + spi { > >>> + #address-cells = <1>; > >>> + #size-cells = <0>; > >>> + > >>> + dmas = <&rx_dma 0>; > >>> + dma-names = "offload0-rx"; > > The dmas aren't related to the ADC, so can be left out of the example. > Ack. > >>> + trigger-sources = <&adc AD4052_TRIGGER_EVENT_DATA_READY > >>> + AD4052_TRIGGER_PIN_GP1>; > >>> + > >>> + adc@0 { > >>> + compatible = "adi,ad4052"; > >>> + reg = <0>; > >>> + vdd-supply = <&vdd>; > >>> + vio-supply = <&vio>; > >>> + spi-max-frequency = <83333333>; > >>> + pwms = <&adc_trigger 0 10000 0>; > >>> + > >>> + #trigger-source-cells = <2>; > >>> + trigger-sources = <&adc AD4052_TRIGGER_EVENT_EITHER_THRESH > >>> + AD4052_TRIGGER_PIN_GP0 > >>> + &adc AD4052_TRIGGER_EVENT_DATA_READY > >>> + AD4052_TRIGGER_PIN_GP1>; > > Same as above - the GP pins aren't wired back to the ADC itself. > > >>> + interrupt-parent = <&gpio>; > >>> + interrupts = <0 0 IRQ_TYPE_EDGE_RISING>, > >>> + <0 1 IRQ_TYPE_EDGE_FALLING>; > >>> + interrupt-names = "gp0", "gp1"; > >>> + cnv-gpios = <&gpio 2 GPIO_ACTIVE_HIGH>; > >>> + }; > >>> + }; Considering the discussion above. As is, in this series GP0 is event Either threshold and GP1 Data ready. A future series would aim to make it truly configurable. For this series then, do we then drop the second cell of trigger cell and do not provide a way of describing the function of each gpio? e.g. - | #include <dt-bindings/gpio/gpio.h> #include <dt-bindings/interrupt-controller/irq.h> #include <dt-bindings/iio/adc/adi,ad4052.h> rx_dma { #dma-cells = <1>; }; spi { #address-cells = <1>; #size-cells = <0>; trigger-sources = <&adc AD4052_TRIGGER_PIN_GP0>; adc@0 { compatible = "adi,ad4052"; reg = <0>; vdd-supply = <&vdd>; vio-supply = <&vio>; spi-max-frequency = <83333333>; pwms = <&adc_trigger 0 10000 0>; // --- Other thought ------ //adi,gpio-role = <AD4052_TRIGGER_EVENT_EITHER_THRESH // AD4052_TRIGGER_EVENT_DATA_READY>; // ------------------------ interrupt-parent = <&gpio>; interrupts = <0 0 IRQ_TYPE_EDGE_RISING>, <0 1 IRQ_TYPE_EDGE_FALLING>; interrupt-names = "gp0", "gp1"; cnv-gpios = <&gpio 2 GPIO_ACTIVE_HIGH>; }; }; Other thought is to add an "adi,gpio-role" property to define gpio function (as commented in the example above, matched with index of interrupts-names). If no interrupt-name.gp0 but trigger-source.GP0, assume role Data ready (no irq for raw read, only buffer offload). What is your opinion on this? Best regards, Jorge
