phy: allwinner: phy-sun4i-usb: Add log when probing

When phy-sun4i-usb's probing fails, it does not print the reason in
kernel log, forcing the developer to edit this driver to add info logs.
This commit makes the kernel print the reason of phy-sun4i-usb's probing
failure or a success message.

Signed-off-by: Quentin Schulz <[e-mail]>
Tested-by: Mylène Josserand <[e-mail]>
Acked-by: Maxime Ripard <[e-mail]>
Signed-off-by: Kishon Vijay Abraham I <[e-mail]>

drivers/phy/allwinner/phy-sun4i-usb.c

···
 
 	data->id_det_gpio = devm_gpiod_get_optional(dev, "usb0_id_det",
 						    GPIOD_IN);
-	if (IS_ERR(data->id_det_gpio))
+	if (IS_ERR(data->id_det_gpio)) {
+		dev_err(dev, "Couldn't request ID GPIO\n");
 		return PTR_ERR(data->id_det_gpio);
+	}
 
 	data->vbus_det_gpio = devm_gpiod_get_optional(dev, "usb0_vbus_det",
 						      GPIOD_IN);
-	if (IS_ERR(data->vbus_det_gpio))
+	if (IS_ERR(data->vbus_det_gpio)) {
+		dev_err(dev, "Couldn't request VBUS detect GPIO\n");
 		return PTR_ERR(data->vbus_det_gpio);
+	}
 
 	if (of_find_property(np, "usb0_vbus_power-supply", NULL)) {
 		data->vbus_power_supply = devm_power_supply_get_by_phandle(dev,
 						     "usb0_vbus_power-supply");
-		if (IS_ERR(data->vbus_power_supply))
+		if (IS_ERR(data->vbus_power_supply)) {
+			dev_err(dev, "Couldn't get the VBUS power supply\n");
 			return PTR_ERR(data->vbus_power_supply);
+		}
 
 		if (!data->vbus_power_supply)
 			return -EPROBE_DEFER;
···
 	data->dr_mode = of_usb_get_dr_mode_by_phy(np, 0);
 
 	data->extcon = devm_extcon_dev_allocate(dev, sun4i_usb_phy0_cable);
-	if (IS_ERR(data->extcon))
+	if (IS_ERR(data->extcon)) {
+		dev_err(dev, "Couldn't allocate our extcon device\n");
 		return PTR_ERR(data->extcon);
+	}
 
 	ret = devm_extcon_dev_register(dev, data->extcon);
 	if (ret) {
···
 		snprintf(name, sizeof(name), "usb%d_vbus", i);
 		phy->vbus = devm_regulator_get_optional(dev, name);
 		if (IS_ERR(phy->vbus)) {
-			if (PTR_ERR(phy->vbus) == -EPROBE_DEFER)
+			if (PTR_ERR(phy->vbus) == -EPROBE_DEFER) {
+				dev_err(dev,
+					"Couldn't get regulator %s... Deferring probe\n",
+					name);
 				return -EPROBE_DEFER;
+			}
+
 			phy->vbus = NULL;
 		}
 
···
 		sun4i_usb_phy_remove(pdev); /* Stop detect work */
 		return PTR_ERR(phy_provider);
 	}
+
+	dev_dbg(dev, "successfully loaded\n");
 
 	return 0;
 }