On Tue, Nov 3, 2020 at 6:39 PM Phil Reid <preid@xxxxxxxxxxxxxxxxx> wrote:
>
> On 4/11/2020 01:28, Jonathan Cameron wrote:
> > On Tue, 3 Nov 2020 10:10:39 -0600
> > Rob Herring <robh@xxxxxxxxxx> wrote:
> >
> >> On Sat, Oct 31, 2020 at 06:48:10PM +0000, Jonathan Cameron wrote:
> >>> From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> >>>
> >>> Simple direct conversion from txt to yaml as part of a general aim of
> >>> converting all IIO bindings to this machine readable format.
> >>>
> >>> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> >>> Cc: Phil Reid <preid@xxxxxxxxxxxxxxxxx>
> >>> ---
> >>> .../bindings/iio/potentiometer/ad5272.txt | 27 ----------
> >>> .../iio/potentiometer/adi,ad5272.yaml | 50 +++++++++++++++++++
> >>> 2 files changed, 50 insertions(+), 27 deletions(-)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/iio/potentiometer/ad5272.txt b/Documentation/devicetree/bindings/iio/potentiometer/ad5272.txt
> >>> deleted file mode 100644
> >>> index f9b2eef946aa..000000000000
> >>> --- a/Documentation/devicetree/bindings/iio/potentiometer/ad5272.txt
> >>> +++ /dev/null
> >>> @@ -1,27 +0,0 @@
> >>> -* Analog Devices AD5272 digital potentiometer
> >>> -
> >>> -The node for this device must be a child node of a I2C controller, hence
> >>> -all mandatory properties for your controller must be specified. See directory:
> >>> -
> >>> - Documentation/devicetree/bindings/i2c
> >>> -
> >>> -for more details.
> >>> -
> >>> -Required properties:
> >>> - - compatible: Must be one of the following, depending on the model:
> >>> - adi,ad5272-020
> >>> - adi,ad5272-050
> >>> - adi,ad5272-100
> >>> - adi,ad5274-020
> >>> - adi,ad5274-100
> >>> -
> >>> -Optional properties:
> >>> - - reset-gpios: GPIO specification for the RESET input. This is an
> >>> - active low signal to the AD5272.
> >>> -
> >>> -Example:
> >>> -ad5272: potentiometer@2f {
> >>> - reg = <0x2F>;
> >>> - compatible = "adi,ad5272-020";
> >>> - reset-gpios = <&gpio3 6 GPIO_ACTIVE_HIGH>;
> >>> -};
> >>> diff --git a/Documentation/devicetree/bindings/iio/potentiometer/adi,ad5272.yaml b/Documentation/devicetree/bindings/iio/potentiometer/adi,ad5272.yaml
> >>> new file mode 100644
> >>> index 000000000000..b9b7d383bff1
> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/iio/potentiometer/adi,ad5272.yaml
> >>> @@ -0,0 +1,50 @@
> >>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> >>> +%YAML 1.2
> >>> +---
> >>> +$id: http://devicetree.org/schemas/iio/potentiometer/adi,ad5272.yaml#
> >>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>> +
> >>> +title: Analog Devices AD5272 digital potentiometer
> >>> +
> >>> +maintainers:
> >>> + - Phil Reid <preid@xxxxxxxxxxxxxxxxx>
> >>> +
> >>> +description: |
> >>> + Datasheet: https://www.analog.com/en/products/ad5272.html
> >>> +
> >>> +properties:
> >>> + compatible:
> >>> + enum:
> >>> + - adi,ad5272-020
> >>> + - adi,ad5272-050
> >>> + - adi,ad5272-100
> >>> + - adi,ad5274-020
> >>> + - adi,ad5274-100
> >>> +
> >>> + reg:
> >>> + maxItems: 1
> >>> +
> >>> + reset-gpios:
> >>> + description:
> >>> + Active low signal to the AD5272 RESET input.
> >>
> >> Not a new problem, but active low or...
> >>
> >>> +
> >>> +additionalProperties: false
> >>> +
> >>> +required:
> >>> + - compatible
> >>> + - reg
> >>> +
> >>> +examples:
> >>> + - |
> >>> + #include <dt-bindings/gpio/gpio.h>
> >>> + i2c {
> >>> + #address-cells = <1>;
> >>> + #size-cells = <0>;
> >>> +
> >>> + potentiometer@2f {
> >>> + compatible = "adi,ad5272-020";
> >>> + reg = <0x2F>;
> >>> + reset-gpios = <&gpio3 6 GPIO_ACTIVE_HIGH>;
> >>
> >> active high?
> >
> > Good spot! @Phil. Looks like the driver is setting the reset line to
> > 0 and then to 1 to come out of reset. So effectively inverting the logic.
> > I'm tempted to be cynical and suggest we just drop the comment above and leave
> > it vague but is there a better way we can clarify this?
>
> Had a look at a few other iio drivers in regards how they handle the same thing.
> A few do the same thing, ie: the drivers are written to set gpio low to assert reset.
> So they need the device tree gpio config to be active high to work correctly.
> Not sure if this prevents users setting things up as open collector.
The driver is wrong. 'gpiod_set_value(reset_gpio, 1);' should assert
reset as '1' here is set to (reset) active state as defined in the DT.
Given no upstream users, maybe it can be fixed...
We need to make 'reset-gpios' implemented by a reset controller and
stop letting drivers get it wrong.
Rob
