Re: [PATCH 5/7] hwmon: (max31790) Clear fan fault after reporting it

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

Fan fault reading/clearing works fine.

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

st 26. 5. 2021 v 17:41 odesílatel Guenter Roeck <linux@roeck-us.net> napsal:
>
> Fault bits in MAX31790 are sticky and have to be cleared explicitly.
> A write operation into either the 'Target Duty Cycle' register or the
> 'Target Count' register is necessary to clear a fault.
>
> At the same time, we can never clear cached fault status values before
> reading them because the companion fault status for any given fan is
> cleared as well when clearing a fault.
>
> Cc: Jan Kundrát <jan.kundrat@cesnet.cz>
> Cc: Václav Kubernát <kubernat@cesnet.cz>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>  drivers/hwmon/max31790.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwmon/max31790.c b/drivers/hwmon/max31790.c
> index 19651feb40fb..8e4fd9b7c889 100644
> --- a/drivers/hwmon/max31790.c
> +++ b/drivers/hwmon/max31790.c
> @@ -80,7 +80,7 @@ static struct max31790_data *max31790_update_device(struct device *dev)
>                                 MAX31790_REG_FAN_FAULT_STATUS1);
>                 if (rv < 0)
>                         goto abort;
> -               data->fault_status = rv & 0x3F;
> +               data->fault_status |= rv & 0x3F;
>
>                 rv = i2c_smbus_read_byte_data(client,
>                                 MAX31790_REG_FAN_FAULT_STATUS2);
> @@ -184,7 +184,21 @@ static int max31790_read_fan(struct device *dev, u32 attr, int channel,
>                 *val = rpm;
>                 return 0;
>         case hwmon_fan_fault:
> +               mutex_lock(&data->update_lock);
>                 *val = !!(data->fault_status & (1 << channel));
> +               data->fault_status &= ~(1 << channel);
> +               /*
> +                * If a fault bit is set, we need to write into one of the fan
> +                * configuration registers to clear it. Note that this also
> +                * clears the fault for the companion channel if enabled.
> +                */
> +               if (*val) {
> +                       int reg = MAX31790_REG_TARGET_COUNT(channel % NR_CHANNEL);
> +
> +                       i2c_smbus_write_byte_data(data->client, reg,
> +                                                 data->target_count[channel % NR_CHANNEL] >> 8);
> +               }
> +               mutex_unlock(&data->update_lock);
>                 return 0;
>         default:
>                 return -EOPNOTSUPP;
> --
> 2.25.1
>