[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: Chris Wright <chrisw@osdl.org>

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index 53cc2b6d63854a835e661a0b2921640b6e36e915..0b0f47c8865ab2df8000316ceecf54c9cdd449ff 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);