RE: [PATCH v2 07/14] dt-bindings: pincfg-node: Add input-voltage-microvolt property

[Yu-Chun Lin [林祐君]]

> On Fri, Mar 06, 2026 at 03:52:37PM +0800, Yu-Chun Lin wrote:
> > From: Tzuyi Chang <tychang@xxxxxxxxxxx>
> >
> > Add a generic pin configuration property "input-voltage-microvolt" to
> > specify the input voltage level of a pin in microvolts.
> 
> Why?
> 
> >
> > Signed-off-by: Tzuyi Chang <tychang@xxxxxxxxxxx>
> > Co-developed-by: Yu-Chun Lin <eleanor.lin@xxxxxxxxxxx>
> > Signed-off-by: Yu-Chun Lin <eleanor.lin@xxxxxxxxxxx>
> > ---
> >  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 a916d0fc79a9..da182c8a1d00 100644
> > --- a/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml
> > +++ b/Documentation/devicetree/bindings/pinctrl/pincfg-node.yaml
> > @@ -162,6 +162,10 @@ properties:
> >        this affects the expected delay in ps before latching a value to
> >        an output pin.
> >
> > +  input-voltage-microvolt:
> > +    description: Specifies the input voltage level of the pin in microvolts.
> > +      This defines the reference for VIH/VIL.
> 
> What is VIH/VIL? Why generic binding would define the voltage of pins for pin
> control?
> 
> This patch misses actual background why you are doing it and what sort of
> common/typical pinctrl setup you describe.
> 
> Best regards,
> Krzysztof

Agreed, the commit message and description lacked sufficient context. I
will improve the explanation in v3.

VIH is Input High Voltage, and VIL is Input Low Voltage.

The reason for introducing 'input-voltage-microvolt' in 'pincfg-node.yaml' is
to support hardware designs where the "Input Logic Threshold" is decoupled
from the "Power Supply Voltage".

For example, a pin might be powered by a fixed 3.3V supply but needs to be
configured to accept 1.8V logic signals. This property allows the pinctrl
driver to set the correct internal reference.

This change follows the suggestion from Linus Walleij [1] to make the property
generic instead of vendor-specific ('realtek,input-voltage'), as the concept
of selecting input thresholds is not unique to Realtek.

[1]: https://lore.kernel.org/all/d5be357c14b84155adfa8a9f00a64d83@xxxxxxxxxxx/

Best regards,
Yu-Chun