Input: elan_i2c - return error code when resume fails

In order to better diagnose potential issues let's return error to the
upper layers when resuming the device fails and also add a few diagnostic
messages.
Signed-off-by: Duson Lin <dusonlin@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/elan_i2c_core.c

@@ -99,7 +99,7 @@ static int elan_enable_power(struct elan_tp_data *data)
 	error = regulator_enable(data->vcc);
 	if (error) {
 		dev_err(&data->client->dev,
-			"Failed to enable regulator: %d\n", error);
+			"failed to enable regulator: %d\n", error);
 		return error;
 	}
 
@@ -111,6 +111,7 @@ static int elan_enable_power(struct elan_tp_data *data)
 		msleep(30);
 	} while (--repeat > 0);
 
+	dev_err(&data->client->dev, "failed to enable power: %d\n", error);
 	return error;
 }
 
@@ -125,7 +126,7 @@ static int elan_disable_power(struct elan_tp_data *data)
 			error = regulator_disable(data->vcc);
 			if (error) {
 				dev_err(&data->client->dev,
-					"Failed to disable regulator: %d\n",
+					"failed to disable regulator: %d\n",
 					error);
 				/* Attempt to power the chip back up */
 				data->ops->power_control(data->client, true);
@@ -138,6 +139,7 @@ static int elan_disable_power(struct elan_tp_data *data)
 		msleep(30);
 	} while (--repeat > 0);
 
+	dev_err(&data->client->dev, "failed to disable power: %d\n", error);
 	return error;
 }
 
@@ -1084,16 +1086,18 @@ static int __maybe_unused elan_resume(struct device *dev)
 	}
 
 	error = elan_enable_power(data);
-	if (error)
+	if (error) {
 		dev_err(dev, "power up when resuming failed: %d\n", error);
+		goto err;
+	}
 
 	error = elan_initialize(data);
 	if (error)
 		dev_err(dev, "initialize when resuming failed: %d\n", error);
 
+err:
 	enable_irq(data->client->irq);
-
-	return 0;
+	return error;
 }
 
 static SIMPLE_DEV_PM_OPS(elan_pm_ops, elan_suspend, elan_resume);

drivers/input/mouse/elan_i2c_i2c.c

@@ -117,7 +117,15 @@ static int elan_i2c_write_cmd(struct i2c_client *client, u16 reg, u16 cmd)
 	int ret;
 
 	ret = i2c_transfer(client->adapter, &msg, 1);
-	return ret == 1 ? 0 : (ret < 0 ? ret : -EIO);
+	if (ret != 1) {
+		if (ret >= 0)
+			ret = -EIO;
+		dev_err(&client->dev, "writing cmd (0x%04x) failed: %d\n",
+			reg, ret);
+		return ret;
+	}
+
+	return 0;
 }
 
 static int elan_i2c_initialize(struct i2c_client *client)