linux-kernel - Re: [PATCH 4/7] dt-bindings: Input: introduce new clock vibrator bindings

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Message-Id: <20200105083534.01EB12071A@mail.kernel.org>
Date:   Sun, 05 Jan 2020 00:35:33 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Brian Masney <masneyb@...tation.org>, dmitry.torokhov@...il.com,
        robh+dt@...nel.org
Cc:     mark.rutland@....com, agross@...nel.org,
        bjorn.andersson@...aro.org, mturquette@...libre.com,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH 4/7] dt-bindings: Input: introduce new clock vibrator bindings

Quoting Brian Masney (2019-12-04 16:25:00)
> diff --git a/Documentation/devicetree/bindings/input/clk-vibrator.yaml b/Documentation/devicetree/bindings/input/clk-vibrator.yaml
> new file mode 100644
> index 000000000000..2103a5694fad
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/clk-vibrator.yaml
> @@ -0,0 +1,60 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/bindings/input/clk-vibrator.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Clock vibrator
> +
> +maintainers:
> +  - Brian Masney <masneyb@...tation.org>
> +
> +description: |
> +  Support for clock-based vibrator devices where the speed can be controlled
> +  by changing the duty cycle.
> +
> +properties:
> +  compatible:
> +    const: clk-vibrator
> +
> +  clocks:
> +    maxItems: 1
> +
> +  clock-names:
> +    description: output clock that controls the speed
> +    items:
> +      - const: core
> +
> +  clock-frequency: true

Can you use assigned-clock-rates for this instead? Then the driver can
call clk_get_rate() if it wants to know the rate that was actually set
on the clk.

> +
> +  enable-gpios:
> +    maxItems: 1
> +
> +  vcc-supply:
> +    description: Regulator that provides power
> +
> +required:
> +  - compatible
> +  - clocks
> +  - clock-names
> +  - clock-frequency
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/qcom,mmcc-msm8974.h>
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    vibrator {
> +        compatible = "clk-vibrator";
> +
> +        vcc-supply = <&pm8941_l19>;
> +
> +        clocks = <&mmcc CAMSS_GP1_CLK>;
> +        clock-names = "core";
> +        clock-frequency = <24000>;
> +
> +        enable-gpios = <&msmgpio 60 GPIO_ACTIVE_HIGH>;
> +
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&vibrator_pin>;

I'm still trying to wrap my head around this. I think we can have a pwm
provider in a clk controller node (so imagine &mmcc has #pwm-cells) and
then this 'clk-vibrator' binding wouldn't exist? Instead we would have
some sort of binding for a device that expects a pwm and whatever else
is required, like the enable gpio and power supply. Is there an actual
hardware block that is this way? Does it have a real product id and is
made by some company? Right now this looks a little too generic to not
just be a catch-all for something that buzzes.