linux-kernel - Re: [PATCH RESEND] ARM: dts: qcom: msm8974-hammerhead: add device tree bindings for vibrator

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Date:   Mon, 20 May 2019 07:21:49 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Brian Masney <masneyb@...tation.org>, agross@...nel.org,
        david.brown@...aro.org
Cc:     bjorn.andersson@...aro.org, robh+dt@...nel.org,
        mark.rutland@....com, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] ARM: dts: qcom: msm8974-hammerhead: add device tree bindings for vibrator

Quoting Brian Masney (2019-05-16 01:50:18)
> @@ -306,6 +307,36 @@
>                                 input-enable;
>                         };
>                 };
> +
> +               vibrator_pin: vibrator {
> +                       pwm {
> +                               pins = "gpio27";
> +                               function = "gp1_clk";
> +
> +                               drive-strength = <6>;
> +                               bias-disable;
> +                       };
> +
> +                       enable {
> +                               pins = "gpio60";
> +                               function = "gpio";
> +                       };
> +               };
> +       };
> +
> +       vibrator@...c3450 {
> +               compatible = "qcom,msm8974-vibrator";
> +               reg = <0xfd8c3450 0x400>;

This is inside the multimedia clk controller. The resource reservation
mechanism should be complaining loudly here. Is the driver writing
directly into clk controller registers to adjust a duty cycle of the
camera's general purpose clk?

Can you add support for duty cycle to the qcom clk driver's RCGs and
then write a generic clk duty cycle vibrator driver that adjusts the
duty cycle of the clk? That would be better than reaching into the clk
controller registers to do this.