On Thu, Aug 20, 2020 at 03:53:41PM +0800, Gene Chen wrote:

+	mrd->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!mrd->regmap) {
+		dev_err(&pdev->dev, "Failed to get parent regmap\n");
+		return -ENODEV;
+	}

+static const struct of_device_id __maybe_unused mt6360_regulator_of_id[] = {
+	{ .compatible = "mediatek,mt6360-regulator", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mt6360_regulator_of_id);

This device only exists in the context of a single parent device, there
should be no need for a compatible string here - this is just a detail
of how Linux does things.  The MFD should just instntiate the platform
device.