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authorGuenter Roeck <linux@roeck-us.net>2021-05-26 08:40:21 -0700
committerGuenter Roeck <linux@roeck-us.net>2021-06-17 04:21:46 -0700
commit1814c4e84de2a89d1c2e1e9bbd241240561075a4 (patch)
treefb83823204e878cafb36d6a7b9f2a8f9c81b5867 /drivers/hwmon/max31790.c
parent2013607b85f03ff24a5a19933705905a1b324a31 (diff)
hwmon: (max31790) Detect and report zero fan speed
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@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/20210526154022.3223012-7-linux@roeck-us.net
Diffstat (limited to 'drivers/hwmon/max31790.c')
-rw-r--r--drivers/hwmon/max31790.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c
index 7927468c5271..7e9362f6dc29 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)
@@ -172,7 +174,10 @@ static int max31790_read_fan(struct device *dev, u32 attr, int channel,
switch (attr) {
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: