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hwmon: (max31790) Clear fan fault after reporting it

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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: Guenter Roeck <linux@roeck-us.net>
Tested-by: Václav Kubernát <kubernat@cesnet.cz>
Link: https://lore.kernel.org/r/20210526154022.3223012-6-linux@roeck-us.net
This commit is contained in:
Guenter Roeck 2021-05-26 08:40:20 -07:00
parent 148c847c9e
commit 2013607b85
1 changed files with 15 additions and 1 deletions
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16
drivers/hwmon/max31790.c
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@ -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;