Re: [PATCH 1/4] dt-bindings: input: Add binding for Qualcomm SPMI PMIC haptics

[Fenglin Wu]

On 6/17/2026 6:35 PM, Krzysztof Kozlowski wrote:
> On Tue, Jun 16, 2026 at 03:08:24AM -0700, Fenglin Wu wrote:
> > ....
> > +
> > +  qcom,lra-period-us:
> > +    description:
> > +      LRA actuator initial resonance period in microseconds
> > +      (1,000,000 / resonant_freq_hz).  Used to configure T_LRA-based play
> > +      rates and the auto-resonance zero-crossing window.
> This does not feel like static characteristic. Isn't period depending on
> intensity of vibration you want to have? Why would that be fixed per
> board?

This period is specifically used for playbacks that require 
auto-resonance to be enabled, which I referred to as "T_LRA-based" and 
"auto-resonance zero-crossing window." It plays a key role in the 
"DIRECT_PLAY" mode, which produces a constant vibration effect. To 
adjust the vibration intensity during this constant effect, the hardware 
does it by scaling the peak voltage of the driver signals, rather than 
changing the frequency.

> > +    minimum: 5
> > +    maximum: 20475
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - reg-names
> > +  - interrupts
> > +  - interrupt-names
> > +  - qcom,vmax-mv
> > +  - qcom,lra-period-us
> > +
> Best regards,
> Krzysztof