Re: [PATCH 2/7] hwmon: (max31790) Report correct current pwm duty cycles

["Václav Kubernát" <kubernat@cesnet.cz>]

PWM duty reading works.

Tested-by: Václav Kubernát <kubernat@ceesnet.cz>

st 26. 5. 2021 v 17:40 odesílatel Guenter Roeck <linux@roeck-us.net> napsal:
>
> 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>
> ---
>  Documentation/hwmon/max31790.rst | 3 ++-
>  drivers/hwmon/max31790.c         | 6 +++---
>  2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/hwmon/max31790.rst b/Documentation/hwmon/max31790.rst
> index f301385d8cef..54ff0f49e28f 100644
> --- a/Documentation/hwmon/max31790.rst
> +++ b/Documentation/hwmon/max31790.rst
> @@ -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)
>  ================== === =======================================================
> diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c
> index f6d4fc0a2f13..693497e09ac0 100644
> --- a/drivers/hwmon/max31790.c
> +++ b/drivers/hwmon/max31790.c
> @@ -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];
> --
> 2.25.1
>