Re: [PATCH] dt-bindings: pincfg-node: Add "input-schmitt" property

[Krzysztof Kozlowski <krzk@kernel.org>]

On 16/07/2024 04:16, Inochi Amaoto wrote:
> On Mon, Jul 15, 2024 at 05:19:41PM GMT, Conor Dooley wrote:
>> On Mon, Jul 15, 2024 at 05:55:28PM +0800, Inochi Amaoto wrote:
>>> On Mon, Jul 15, 2024 at 11:21:25AM GMT, Krzysztof Kozlowski wrote:
>>>> On 14/07/2024 13:28, Inochi Amaoto wrote:
>>>>> On Sophgo CV18XX platform, threshold strength of schmitt trigger can
>>>>> be configured. As this standard property is already supported by the
>>>>> common pinconf code. Add "input-schmitt" property in pincfg-node.yaml
>>>>> so that other platforms requiring such feature can make use of this
>>>>> property.
>>>>>
>>>>> Signed-off-by: Inochi Amaoto <inochiama@outlook.com>
>>>>> ---
>>>>>  Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml | 4 ++++
>>>>>  1 file changed, 4 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml b/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml
>>>>> index d0af21a564b4..e838fcac7f2a 100644
>>>>> --- a/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml
>>>>> +++ b/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml
>>>>> @@ -88,6 +88,10 @@ properties:
>>>>>      description: disable input on pin (no effect on output, such as
>>>>>        disabling an input buffer)
>>>>>
>>>>> +  input-schmitt:
>>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>>> +    description: threshold strength for schmitt-trigger
>>>>
>>>> Strength in which units? This should have proper property name suffix.
>>>>
>>>
>>> I think it should be mV. Using voltage may leads to decimal.
>>
>> The standard suffix for voltage is "-microvolts", so no issues with
>> decimals :) And with a standard suffix, the $ref can be dropped.
> 
> Yeah, I have seen the "-microvolts", but I does not think add standard
> suffix is a good idea, as "input-schmitt" is a standard pinconf attribute.
> 
> The only thing confused me is that the description of PIN_CONFIG_INPUT_SCHMITT 
> in include/linux/pinctrl/pinconf-generic.h says it just uses an custom

You cannot add binding based on argument "I don't want to change kernel
code", so sorry, but it does not really matter whatever pinctrl has
undocumented.

> format as argument. So I think it may keep something generic?
> 

Best regards,
Krzysztof