If a fan is not running or not connected, of if fan monitoring is disabled, the fan count register returns a fixed value of 0xffe0. So far this is then translated to a RPM value larger than 0. Since this is misleading and does not really make much sense, report a fan RPM of 0 in this situation. Cc: Jan Kundrát <jan.kundrat@xxxxxxxxx> Cc: Václav Kubernát <kubernat@xxxxxxxxx> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> --- drivers/hwmon/max31790.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c index 8e4fd9b7c889..91fe419b596c 100644 --- a/drivers/hwmon/max31790.c +++ b/drivers/hwmon/max31790.c @@ -40,6 +40,8 @@ #define FAN_RPM_MIN 120 #define FAN_RPM_MAX 7864320 +#define FAN_COUNT_REG_MAX 0xffe0 + #define RPM_FROM_REG(reg, sr) (((reg) >> 4) ? \ ((60 * (sr) * 8192) / ((reg) >> 4)) : \ FAN_RPM_MAX) @@ -175,7 +177,10 @@ static int max31790_read_fan(struct device *dev, u32 attr, int channel, return 0; case hwmon_fan_input: sr = get_tach_period(data->fan_dynamics[channel % NR_CHANNEL]); - rpm = RPM_FROM_REG(data->tach[channel], sr); + if (data->tach[channel] == FAN_COUNT_REG_MAX) + rpm = 0; + else + rpm = RPM_FROM_REG(data->tach[channel], sr); *val = rpm; return 0; case hwmon_fan_target: -- 2.25.1
