hwmon: (w83795) Only start monitoring if needed

This saves an SMBus write if monitoring was already enabled. Signed-off-by: Jean Delvare <[email protected]>
devinus · Oct 28, 2010 · 80646b9 · 80646b9
1 parent 86ef4d2
commit 80646b9
Showing 1 changed file with 10 additions and 3 deletions.
diff --git a/drivers/hwmon/w83795.c b/drivers/hwmon/w83795.c
@@ -55,6 +55,7 @@ MODULE_PARM_DESC(reset, "Set to 1 to reset chip, not recommended");
 #define W83795_REG_I2C_ADDR		0xfc
 #define W83795_REG_CONFIG		0x01
 #define W83795_REG_CONFIG_CONFIG48	0x04
+#define W83795_REG_CONFIG_START	0x01
 
 /* Multi-Function Pin Ctrl Registers */
 #define W83795_REG_VOLT_CTRL1		0x02
@@ -1664,12 +1665,18 @@ static const struct sensor_device_attribute_2 sda_single_files[] = {
 
 static void w83795_init_client(struct i2c_client *client)
 {
+	u8 config;
+
 	if (reset)
 		w83795_write(client, W83795_REG_CONFIG, 0x80);
 
-	/* Start monitoring */
-	w83795_write(client, W83795_REG_CONFIG,
-		     w83795_read(client, W83795_REG_CONFIG) | 0x01);
+	/* Start monitoring if needed */
+	config = w83795_read(client, W83795_REG_CONFIG);
+	if (!(config & W83795_REG_CONFIG_START)) {
+		dev_info(&client->dev, "Enabling monitoring operations\n");
+		w83795_write(client, W83795_REG_CONFIG,
+			     config | W83795_REG_CONFIG_START);
+	}
 }
 
 static int w83795_get_device_id(struct i2c_client *client)