power_supply: isp1704_charger: Error messages when probe fail

This patch adds more detailed error messages when probe function fails.
It is useful for debbuging why the driver refuses to register the
charger device.
Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/isp1704_charger.c

@@ -411,8 +411,10 @@ static int isp1704_charger_probe(struct platform_device *pdev)
 	if (np) {
 		int gpio = of_get_named_gpio(np, "nxp,enable-gpio", 0);
 
-		if (gpio < 0)
+		if (gpio < 0) {
+			dev_err(&pdev->dev, "missing DT GPIO nxp,enable-gpio\n");
 			return gpio;
+		}
 
 		pdata = devm_kzalloc(&pdev->dev,
 			sizeof(struct isp1704_charger_data), GFP_KERNEL);
@@ -422,8 +424,10 @@ static int isp1704_charger_probe(struct platform_device *pdev)
 
 		ret = devm_gpio_request_one(&pdev->dev, pdata->enable_gpio,
 					GPIOF_OUT_INIT_HIGH, "isp1704_reset");
-		if (ret)
+		if (ret) {
+			dev_err(&pdev->dev, "gpio request failed\n");
 			goto fail0;
+		}
 	}
 
 	if (!pdata) {
@@ -443,6 +447,7 @@ static int isp1704_charger_probe(struct platform_device *pdev)
 
 	if (IS_ERR(isp->phy)) {
 		ret = PTR_ERR(isp->phy);
+		dev_err(&pdev->dev, "usb_get_phy failed\n");
 		goto fail0;
 	}
 
@@ -452,8 +457,10 @@ static int isp1704_charger_probe(struct platform_device *pdev)
 	isp1704_charger_set_power(isp, 1);
 
 	ret = isp1704_test_ulpi(isp);
-	if (ret < 0)
+	if (ret < 0) {
+		dev_err(&pdev->dev, "isp1704_test_ulpi failed\n");
 		goto fail1;
+	}
 
 	isp->psy_desc.name		= "isp1704";
 	isp->psy_desc.type		= POWER_SUPPLY_TYPE_USB;
@@ -466,6 +473,7 @@ static int isp1704_charger_probe(struct platform_device *pdev)
 	isp->psy = power_supply_register(isp->dev, &isp->psy_desc, &psy_cfg);
 	if (IS_ERR(isp->psy)) {
 		ret = PTR_ERR(isp->psy);
+		dev_err(&pdev->dev, "power_supply_register failed\n");
 		goto fail1;
 	}
 
@@ -478,8 +486,10 @@ static int isp1704_charger_probe(struct platform_device *pdev)
 	isp->nb.notifier_call = isp1704_notifier_call;
 
 	ret = usb_register_notifier(isp->phy, &isp->nb);
-	if (ret)
+	if (ret) {
+		dev_err(&pdev->dev, "usb_register_notifier failed\n");
 		goto fail2;
+	}
 
 	dev_info(isp->dev, "registered with product id %s\n", isp->model);