linux-kernel - Re: [PATCH V2] iio: magnetometer: mag3110: add optional vdd/vddio regulator operation support

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Date:   Mon, 10 Dec 2018 16:19:14 +0800
From:   Phil Reid <preid@...ctromag.com.au>
To:     Anson Huang <anson.huang@....com>,
        "jic23@...nel.org" <jic23@...nel.org>,
        "knaack.h@....de" <knaack.h@....de>,
        "lars@...afoo.de" <lars@...afoo.de>,
        "pmeerw@...erw.net" <pmeerw@...erw.net>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "festevam@...il.com" <festevam@...il.com>
Cc:     dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH V2] iio: magnetometer: mag3110: add optional vdd/vddio
 regulator operation support

G'day Anson,

On 10/12/2018 3:17 PM, Anson Huang wrote:
> The magnetometer's power supply could be controlled by regulator
> on some platforms, such as i.MX6Q-SABRESD board, the mag3110's
> power supply is controlled by a GPIO fixed regulator, need to make
> sure the regulator is enabled before any communication with mag3110,
> this patch adds optional vdd/vddio regulator operation support.
> 

[snip]

> +
> +	data->vdd_reg = devm_regulator_get_optional(&client->dev, "vdd");
> +	if (!IS_ERR(data->vdd_reg)) {
> +		ret = regulator_enable(data->vdd_reg);
> +		if (ret) {
> +			dev_err(&client->dev, "failed to enable VDD regulator\n");
> +			return ret;
> +		}
> +	} else if (data->vdd_reg == ERR_PTR(-EPROBE_DEFER)) {
> +		return -EPROBE_DEFER;
> +	}
> +
IANAE, but normally the return pattern for devm_regulator_get_optional

if (!IS_ERR(reg)) {
     regulator_enable ...
} else {
     ret = PTR_ERR(reg);
     if (ret != -ENODEV)
         return ret;
}



-- 
Regards
Phil