Re: [PATCH v2 1/3] dt-bindings: adc-joystick: add adc-joystick,polled option

[Artur Rojek <contact@artur-rojek.eu>]

On 2022-06-03 07:33, Krzysztof Kozlowski wrote:
> On 02/06/2022 21:44, Chris Morgan wrote:
>> On Thu, Jun 02, 2022 at 11:56:10AM +0200, Krzysztof Kozlowski wrote:
>>> On 01/06/2022 22:49, Chris Morgan wrote:
>>>> From: Chris Morgan <macromorgan@hotmail.com>
>>>> 
>>>> Add documentation for adc-joystick,polled. New device-tree 
>>>> properties
>>>> have been added.
>>>> 
>>>> - adc-joystick,polled: A boolean value noting the joystick device
>>>> 		       should be polled rather than use a triggered
>>>> 		       buffer.
>>>> 
>>>> Signed-off-by: Maya Matuszczyk <maccraft123mc@gmail.com>
>>>> Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
>>>> ---
>>>>  .../devicetree/bindings/input/adc-joystick.yaml          | 9 
>>>> ++++++++-
>>>>  1 file changed, 8 insertions(+), 1 deletion(-)
>>>> 
>>>> diff --git 
>>>> a/Documentation/devicetree/bindings/input/adc-joystick.yaml 
>>>> b/Documentation/devicetree/bindings/input/adc-joystick.yaml
>>>> index 2ee04e03bc22..4f49a1a5772e 100644
>>>> --- a/Documentation/devicetree/bindings/input/adc-joystick.yaml
>>>> +++ b/Documentation/devicetree/bindings/input/adc-joystick.yaml
>>>> @@ -12,12 +12,19 @@ maintainers:
>>>> 
>>>>  description: >
>>>>    Bindings for joystick devices connected to ADC controllers 
>>>> supporting
>>>> -  the Industrial I/O subsystem.
>>>> +  the Industrial I/O subsystem. Supports both polled devices where 
>>>> no
>>>> +  iio trigger is available and non-polled devices which are 
>>>> triggered
>>>> +  by iio.
>>>> 
>>>>  properties:
>>>>    compatible:
>>>>      const: adc-joystick
>>>> 
>>>> +  adc-joystick,polled:
>>>> +    type: boolean
>>>> +    description:
>>>> +      If the device does not support triggered buffers and needs to 
>>>> be polled.
>>> 
>> 
>> What would your recommendation be? I'm basically proposing polling
>> instead of utilizing a triggered buffer, so instead of the driver
>> relying on a hardware trigger or a software trigger being set up to
>> fill the buffer that is read by the input subsystem we use the input
>> subsystem polling function directly (this is useful for my use-case
>> where the Rockchip SARADC doesn't have a hardware trigger).
> 
> Then it could be: "adc-joystik,no-hardware-trigger". The description is
> I think accurate, so just the property name.

Hmm... I don't think DT involvement is necessary here, as this 
information can be derived from iio at runtime:
`if (iio_dev->modes & INDIO_BUFFER_SOFTWARE)` - a buffer can be used,
`if (iio_dev->modes & INDIO_DIRECT_MODE)` - device can be polled.

Cheers,
Artur
> 
> 
> 
> Best regards,
> Krzysztof