The w83627ehf driver changes the fan clock divider automatically when a new min fan speed is set. It is supposed to preserve the fan speed reading while doing so, bug doesn't really. Fix it. Signed-off-by: Jean Delvare <khali at linux-fr.org> --- drivers/hwmon/w83627ehf.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) --- linux-2.6.22-rc5.orig/drivers/hwmon/w83627ehf.c 2007-06-16 23:02:58.000000000 +0200 +++ linux-2.6.22-rc5/drivers/hwmon/w83627ehf.c 2007-06-17 15:46:59.000000000 +0200 @@ -716,10 +716,15 @@ store_fan_min(struct device *dev, struct /* Write both the fan clock divider (if it changed) and the new fan min (unconditionally) */ if (new_div != data->fan_div[nr]) { - if (new_div > data->fan_div[nr]) - data->fan[nr] >>= (data->fan_div[nr] - new_div); - else - data->fan[nr] <<= (new_div - data->fan_div[nr]); + /* Preserve the fan speed reading */ + if (data->fan[nr] != 0xff) { + if (new_div > data->fan_div[nr]) + data->fan[nr] >>= new_div - data->fan_div[nr]; + else if (data->fan[nr] & 0x80) + data->fan[nr] = 0xff; + else + data->fan[nr] <<= data->fan_div[nr] - new_div; + } dev_dbg(dev, "fan%u clock divider changed from %u to %u\n", nr + 1, div_from_reg(data->fan_div[nr]), -- Jean Delvare