hwmon: (lm90) Fix handling of hysteresis value (ec38fa2b) · Commits · 戴 / test

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>

drivers/hwmon/lm90.c

+12 −3

Original line number	Diff line number	Diff line
		@@ -461,6 +461,8 @@ static ssize_t show_temphyst(struct device dev, struct device_attribute devatt

		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 @@ static ssize_t set_temphyst(struct device dev, struct device_attribute dummy,
		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;
		}

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