Commit 2013607b authored by Guenter Roeck's avatar Guenter Roeck
Browse files

hwmon: (max31790) Clear fan fault after reporting it 



Fault bits in MAX31790 are sticky and have to be cleared explicitly.
A write operation into either the 'Target Duty Cycle' register or the
'Target Count' register is necessary to clear a fault.

At the same time, we can never clear cached fault status values before
reading them because the companion fault status for any given fan is
cleared as well when clearing a fault.

Cc: Jan Kundrát <jan.kundrat@cesnet.cz>
Cc: Václav Kubernát <kubernat@cesnet.cz>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Tested-by: default avatarVáclav Kubernát <kubernat@cesnet.cz>
Link: https://lore.kernel.org/r/20210526154022.3223012-6-linux@roeck-us.net
parent 148c847c

drivers/hwmon/max31790.c

+15 −1
Original line number Diff line number Diff line
@@ -80,7 +80,7 @@ static struct max31790_data *max31790_update_device(struct device *dev) 
				MAX31790_REG_FAN_FAULT_STATUS1);

		if (rv < 0)

			goto abort;

		data->fault_status = rv & 0x3F;

		data->fault_status |= rv & 0x3F;



		rv = i2c_smbus_read_byte_data(client,

				MAX31790_REG_FAN_FAULT_STATUS2);
@@ -181,7 +181,21 @@ static int max31790_read_fan(struct device *dev, u32 attr, int channel, 
		*val = rpm;

		return 0;

	case hwmon_fan_fault:

		mutex_lock(&data->update_lock);

		*val = !!(data->fault_status & (1 << channel));

		data->fault_status &= ~(1 << channel);

		/*

		 * If a fault bit is set, we need to write into one of the fan

		 * configuration registers to clear it. Note that this also

		 * clears the fault for the companion channel if enabled.

		 */

		if (*val) {

			int reg = MAX31790_REG_TARGET_COUNT(channel % NR_CHANNEL);



			i2c_smbus_write_byte_data(data->client, reg,

						  data->target_count[channel % NR_CHANNEL] >> 8);

		}

		mutex_unlock(&data->update_lock);

		return 0;

	default:

		return -EOPNOTSUPP;