Don't rely on the register cache when setting a new fan clock divider. For one thing, the cache might not have been initialized at all if the driver has just been loaded. For another, the cached values may be old and you never know what can happen in the driver's back. Also invalidate the cache instead of trying to adjust the measured fan speed: the whole point of changing the clock divider is to get a better reading. Signed-off-by: Jean Delvare <khali at linux-fr.org> --- drivers/hwmon/adm1031.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- linux-2.6.24-rc3.orig/drivers/hwmon/adm1031.c 2007-12-01 10:18:09.000000000 +0100 +++ linux-2.6.24-rc3/drivers/hwmon/adm1031.c 2007-12-02 22:22:18.000000000 +0100 @@ -542,18 +542,26 @@ set_fan_div(struct device *dev, const ch return -EINVAL; mutex_lock(&data->update_lock); + /* Get fresh readings */ + data->fan_div[nr] = adm1031_read_value(client, + ADM1031_REG_FAN_DIV(nr)); + data->fan_min[nr] = adm1031_read_value(client, + ADM1031_REG_FAN_MIN(nr)); + + /* Write the new clock divider and fan min */ old_div = FAN_DIV_FROM_REG(data->fan_div[nr]); data->fan_div[nr] = (tmp & 0xC0) | (0x3f & data->fan_div[nr]); new_min = data->fan_min[nr] * old_div / FAN_DIV_FROM_REG(data->fan_div[nr]); data->fan_min[nr] = new_min > 0xff ? 0xff : new_min; - data->fan[nr] = data->fan[nr] * old_div / - FAN_DIV_FROM_REG(data->fan_div[nr]); adm1031_write_value(client, ADM1031_REG_FAN_DIV(nr), data->fan_div[nr]); adm1031_write_value(client, ADM1031_REG_FAN_MIN(nr), data->fan_min[nr]); + + /* Invalidate the cache: fan speed is no longer valid */ + data->valid = 0; mutex_unlock(&data->update_lock); return count; } -- Jean Delvare
