linux-kernel - Re: [RFC 09/10] misc: hisi_hikey

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Message-ID: <20200904122303.GC4625@sirena.org.uk>
Date:   Fri, 4 Sep 2020 13:23:03 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc:     linuxarm@...wei.com, mauro.chehab@...wei.com,
        John Stultz <john.stultz@...aro.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC 09/10] misc: hisi_hikey_usb: add support for Hikey 970

On Fri, Sep 04, 2020 at 12:23:31PM +0200, Mauro Carvalho Chehab wrote:

> +	regulator = devm_regulator_get_optional(&pdev->dev, "hub-vdd");
> +	if (IS_ERR(regulator)) {
> +		if (PTR_ERR(regulator) == -EPROBE_DEFER) {
> +			dev_info(&pdev->dev,
> +				 "waiting for hub-vdd-supply to be probed\n");
> +			return PTR_ERR(regulator);
> +		}
> +
> +		/* let it fall back to regulator dummy */
> +		regulator = devm_regulator_get(&pdev->dev, "hub-vdd");
> +		if (IS_ERR(regulator)) {
> +			dev_err(&pdev->dev,
> +				"get hub-vdd-supply failed with error %ld\n",
> +				PTR_ERR(regulator));
> +			return PTR_ERR(regulator);
> +		}
> +	}

This seems weird - if the supply is non-optional why is the code trying
with devm_regulator_get_optional()?  Just use normal get directly.

> +	ret = regulator_set_voltage(regulator, 3300000, 3300000);
> +	if (ret)
> +		dev_err(&pdev->dev, "set hub-vdd-supply voltage failed\n");

Unless the device is actively managing the voltage at runtime it should
just let the voltage be set by machine constraints, most of the time
this will do nothing.  This only sets the voltage in this one place.

> +	hub_reset_en_gpio = of_get_named_gpio(pdev->dev.of_node,
> +					      "hub_reset_en_gpio", 0);
> +	if (!gpio_is_valid(hub_reset_en_gpio)) {
> +		dev_err(&pdev->dev, "Failed to get a valid reset gpio\n");
> +		return -ENODEV;
> +	}

Why not just use devm_gpio_request() which already asks for the GPIO by
name?

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