[PATCH] hwmon: Fix missing it87 fan div init

Fix a bug where setting the low fan speed limits will not work if no
data was ever read through the sysfs interface and the fan clock
dividers have not been explicitely set yet either. The reason is that
data->fan_div[nr] may currently be used before it is initialized from
the chip register values. The fix is to explicitely initialize
data->fan_div[nr] before using it.

Bug reported, and fix tested, by Nicolas Mailhot.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index 6c41e25..a61f5d0 100644 (file)
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -522,8 +522,15 @@ static ssize_t set_fan_min(struct device *dev, struct device_attribute *attr,
        struct i2c_client *client = to_i2c_client(dev);
        struct it87_data *data = i2c_get_clientdata(client);
        int val = simple_strtol(buf, NULL, 10);
+       u8 reg = it87_read_value(client, IT87_REG_FAN_DIV);
 
        down(&data->update_lock);
+       switch (nr) {
+       case 0: data->fan_div[nr] = reg & 0x07; break;
+       case 1: data->fan_div[nr] = (reg >> 3) & 0x07; break;
+       case 2: data->fan_div[nr] = (reg & 0x40) ? 3 : 1; break;
+       }
+
        data->fan_min[nr] = FAN_TO_REG(val, DIV_FROM_REG(data->fan_div[nr]));
        it87_write_value(client, IT87_REG_FAN_MIN(nr), data->fan_min[nr]);
        up(&data->update_lock);