hwmon: (lm90) Fix handling of hysteresis value
There are several problems in the way the hysteresis value is handled
by the lm90 driver:
* In show_temphyst(), specific handling of the MAX6646 is missing, so
the hysteresis is reported incorrectly if the critical temperature
is over 127 degrees C.
* In set_temphyst(), the new hysteresis register value is written to
the chip but data->temp_hyst isn't updated accordingly, so there is
a short period of time (up to 2 seconds) where the old hystereris
value will be returned while the new one is already active.
* In set_temphyst(), the critical temperature which is used as a base
to compute the value of the hysteresis register lacks
device-specific handling. As a result, the value of the hysteresis
register might be incorrect for the ADT7461 and MAX6646 chips.
Fix these 3 bugs.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Nate Case <ncase@xes-inc.com>
diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index 3edeebc..6242e72 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -461,6 +461,8 @@
if (data->kind == adt7461)
temp = temp_from_u8_adt7461(data, data->temp8[attr->index]);
+ else if (data->kind == max6646)
+ temp = temp_from_u8(data->temp8[attr->index]);
else
temp = temp_from_s8(data->temp8[attr->index]);
@@ -473,12 +475,19 @@
struct i2c_client *client = to_i2c_client(dev);
struct lm90_data *data = i2c_get_clientdata(client);
long val = simple_strtol(buf, NULL, 10);
- long hyst;
+ int temp;
mutex_lock(&data->update_lock);
- hyst = temp_from_s8(data->temp8[2]) - val;
+ if (data->kind == adt7461)
+ temp = temp_from_u8_adt7461(data, data->temp8[2]);
+ else if (data->kind == max6646)
+ temp = temp_from_u8(data->temp8[2]);
+ else
+ temp = temp_from_s8(data->temp8[2]);
+
+ data->temp_hyst = hyst_to_reg(temp - val);
i2c_smbus_write_byte_data(client, LM90_REG_W_TCRIT_HYST,
- hyst_to_reg(hyst));
+ data->temp_hyst);
mutex_unlock(&data->update_lock);
return count;
}