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hwmon: (max31790) Report correct current pwm duty cycles 

The MAX31790 has two sets of registers for pwm duty cycles, one to request
a duty cycle and one to read the actual current duty cycle. Both do not
have to be the same.

When reporting the pwm duty cycle to the user, the actual pwm duty cycle
from pwm duty cycle registers needs to be reported. When setting it, the
pwm target duty cycle needs to be written. Since we don't know the actual
pwm duty cycle after a target pwm duty cycle has been written, set the
valid flag to false to indicate that actual pwm duty cycle should be read
from the chip instead of using cached values.

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@ceesnet.cz>
Reviewed-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Link: https://lore.kernel.org/r/20210526154022.3223012-3-linux@roeck-us.net
This commit is contained in:
Guenter Roeck 2021-05-26 08:40:17 -07:00
parent cbbf244f05
commit 897f633989
2 changed files with 5 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/hwmon/max31790.rst
View File

@ -39,5 +39,6 @@ fan[1-12]_input RO fan tachometer speed in RPM
fan[1-12]_fault RO fan experienced fault
fan[1-6]_target RW desired fan speed in RPM
pwm[1-6]_enable RW regulator mode, 0=disabled, 1=manual mode, 2=rpm mode
pwm[1-6] RW fan target duty cycle (0-255)
pwm[1-6] RW read: current pwm duty cycle,
write: target pwm duty cycle (0-255)
================== === =======================================================

6
drivers/hwmon/max31790.c
View File

@ -104,7 +104,7 @@ static struct max31790_data *max31790_update_device(struct device *dev)
data->tach[NR_CHANNEL + i] = rv;
} else {
rv = i2c_smbus_read_word_swapped(client,
MAX31790_REG_PWMOUT(i));
MAX31790_REG_PWM_DUTY_CYCLE(i));
if (rv < 0)
goto abort;
data->pwm[i] = rv;
@ -299,10 +299,10 @@ static int max31790_write_pwm(struct device *dev, u32 attr, int channel,
err = -EINVAL;
break;
}
data->pwm[channel] = val << 8;
data->valid = false;
err = i2c_smbus_write_word_swapped(client,
MAX31790_REG_PWMOUT(channel),
data->pwm[channel]);
val << 8);
break;
case hwmon_pwm_enable:
fan_config = data->fan_config[channel];