linux-kernel - Re: [PATCH v2 3/3] arm64: dts: qcom: sc7280: Add wcd9380 pinmux

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Date:   Wed, 9 Feb 2022 16:03:30 -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 3/3] arm64: dts: qcom: sc7280: Add wcd9380 pinmux

Quoting Srinivasa Rao Mandadapu (2022-02-09 06:26:58)
>
> On 2/9/2022 2:42 AM, Stephen Boyd wrote:
> > Quoting Srinivasa Rao Mandadapu (2022-02-08 07:34:14)
> >
> >> +                       pins = "gpio83";
> >> +                       function = "gpio";
> >> +                       drive-strength = <16>;
> >> +                       output-high;
> >> +       };
> >> +
> >> +       wcd938x_reset_sleep: wcd938x_reset_sleep {
> >> +                       pins = "gpio83";
> >> +                       function = "gpio";
> >> +                       drive-strength = <16>;
> >> +                       bias-disable;
> >> +                       output-low;
> > Why doesn't the device drive the reset gpio by requesting the gpio and
> > asserting and deasserting it? We shouldn't need to use pinctrl settings
> > to toggle reset gpios.
> Okay. Verified without these nodes and didn't see any impact. But
> similar way it's mentioned in sm8250-mtp.dts. Could You please suggest
> on it how to go ahead on this?.

I'd expect the wcd938x codec device node to have a 'reset-gpios'
property like

	reset-gpios = <&tlmm 83 GPIO_ACTIVE_LOW>

and then the driver to request that gpio via

	reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);

so it gets the gpio during driver probe. Then the gpio can be deasserted
during suspend and reasserted on resume, if that's even important?