From: Guenter Roeck linux@roeck-us.net
stable inclusion from linux-4.19.198 commit 96d87260d3e1878c3d48f57d84493d3c1a9f7b89
--------------------------------
[ Upstream commit cbbf244f0515af3472084f22b6213121b4a63835 ]
Fans 7..12 do not have their own set of configuration registers. So far the code ignored that and read beyond the end of the configuration register range to get the tachometer period. This resulted in more or less random fan speed values for those fans.
The datasheet is quite vague when it comes to defining the tachometer period for fans 7..12. Experiments confirm that the period is the same for both fans associated with a given set of configuration registers.
Fixes: 54187ff9d766 ("hwmon: (max31790) Convert to use new hwmon registration API") Fixes: 195a4b4298a7 ("hwmon: Driver for Maxim MAX31790") Cc: Jan Kundrát jan.kundrat@cesnet.cz Reviewed-by: Jan Kundrát jan.kundrat@cesnet.cz Cc: Václav Kubernát kubernat@cesnet.cz Reviewed-by: Jan Kundrát jan.kundrat@cesnet.cz Signed-off-by: Guenter Roeck linux@roeck-us.net Link: https://lore.kernel.org/r/20210526154022.3223012-2-linux@roeck-us.net Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/hwmon/max31790.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c index 281491cca5103..66cf772de7d29 100644 --- a/drivers/hwmon/max31790.c +++ b/drivers/hwmon/max31790.c @@ -179,7 +179,7 @@ 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]); + sr = get_tach_period(data->fan_dynamics[channel % NR_CHANNEL]); rpm = RPM_FROM_REG(data->tach[channel], sr); *val = rpm; return 0;