linux-kernel - Re: [PATCH v2 2/3] arm64: dts: qcom: sc7280: add lpass lpi pin controller node

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Date:   Wed, 9 Feb 2022 16:05:52 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>,
        agross@...nel.org, bjorn.andersson@...aro.org,
        devicetree@...r.kernel.org, dianders@...omium.org,
        judyhsiao@...omium.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, robh+dt@...nel.org,
        rohitkr@...eaurora.org, srinivas.kandagatla@...aro.org
Cc:     Venkata Prasad Potturu <quic_potturu@...cinc.com>
Subject: Re: [PATCH v2 2/3] arm64: dts: qcom: sc7280: add lpass lpi pin
 controller node

Quoting Srinivasa Rao Mandadapu (2022-02-09 06:01:21)
>
> On 2/9/2022 2:41 AM, Stephen Boyd wrote:
> > Quoting Srinivasa Rao Mandadapu (2022-02-08 07:34:13)
> >> +                       data {
> >> +                               pins = "gpio7";
> >> +                               function = "dmic1_data";
> >> +                               drive-strength = <8>;
> >> +                               input-enable;
> >> +                       };
> >> +               };
> >> +
> >> +               dmic01_sleep: dmic01-sleep-pins {
> >> +                       clk {
> >> +                               pins = "gpio6";
> >> +                               function = "dmic1_clk";
> >> +                               drive-strength = <2>;
> >> +                               bias-disable;
> >> +                               output-low;
> >> +                       };
> >> +
> >> +                       data {
> >> +                               pins = "gpio7";
> >> +                               function = "dmic1_data";
> >> +                               drive-strength = <2>;
> >> +                               pull-down;
> >> +                               input-enable;
> > Why does input-enable matter? It's not a gpio.
> Actually the same is fallowed in sm8250.dtsi. Verified without it and
> working fine. Need take call on it.

Is that because the pin is already an input by default? What does gpio
debugfs say for this pin? Does it also work if you make it
output-low/output-high here? I thought that the gpio itself isn't muxed
out to the pad unless the function is "gpio" so I hope the input/output
settings have no effect here.