Re: [PATCH] hwmon: (max31790) add fanN_enable

From: Guenter Roeck
Date: Mon Aug 29 2022 - 12:11:44 EST

On Mon, Aug 29, 2022 at 08:09:21AM -0700, Justin Ledford wrote:
> The tach input isn't enabled in the device by default. So the only way
> to start using the fan input sensors is to set the regulator mode
> through the driver to RPM mode and then back to whatever mode you
> actually want to use. The I2C interface to the device doesn't couple
> the tach input to the regulator mode so I don't think it makes sense
> for the driver to do this either.
>
Please don't top-post.

The above does not answer my question why fan_config[] wound need to
be updated repeatedly.

Guenter

> On Mon, Aug 29, 2022 at 6:20 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> >
> > On Mon, Aug 29, 2022 at 02:43:51AM +0000, Justin Ledford wrote:
> > > The MAX31790 has a tach input enable bit in each fan's configuration
> > > register. This is only enabled by the driver if RPM mode is selected,
> > > but the driver doesn't provide a way to independently enable tachometer
> > > input regardless of the regulator mode.
> > >
> > > By adding the fanN_enable sysfs files, we can decouple the tach input
> > > from the regulator mode. Also update the documentation.
> > >
> > > Signed-off-by: Justin Ledford <justinledford@xxxxxxxxxx>
> > > ---
> > > Documentation/hwmon/max31790.rst | 1 +
> > > drivers/hwmon/max31790.c | 44 +++++++++++++++++++++++++++-----
> > > 2 files changed, 38 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/Documentation/hwmon/max31790.rst b/Documentation/hwmon/max31790.rst
> > > index 7b097c3b9b90..33c5c7330efc 100644
> > > --- a/Documentation/hwmon/max31790.rst
> > > +++ b/Documentation/hwmon/max31790.rst
> > > @@ -38,6 +38,7 @@ Sysfs entries
> > > 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
> > > +fan[1-6]_enable RW enable or disable the tachometer input
> > > pwm[1-6]_enable RW regulator mode, 0=disabled (duty cycle=0%), 1=manual mode, 2=rpm mode
> > > 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 7e9362f6dc29..3ae02be4b41e 100644
> > > --- a/drivers/hwmon/max31790.c
> > > +++ b/drivers/hwmon/max31790.c
> > > @@ -118,6 +118,12 @@ static struct max31790_data *max31790_update_device(struct device *dev)
> > > goto abort;
> > > data->target_count[i] = rv;
> > > }
> > > +
> > > + rv = i2c_smbus_read_byte_data(client,
> > > + MAX31790_REG_FAN_CONFIG(i));
> > > + if (rv < 0)
> > > + goto abort;
> > > + data->fan_config[i] = rv;
> >
> > Why is this needed ?
> >
> > Guenter
> >
> > > }
> > >
> > > data->last_updated = jiffies;
> > > @@ -202,6 +208,9 @@ static int max31790_read_fan(struct device *dev, u32 attr, int channel,
> > > }
> > > mutex_unlock(&data->update_lock);
> > > return 0;
> > > + case hwmon_fan_enable:
> > > + *val = !!(data->fan_config[channel] & MAX31790_FAN_CFG_TACH_INPUT_EN);
> > > + return 0;
> > > default:
> > > return -EOPNOTSUPP;
> > > }
> > > @@ -214,7 +223,7 @@ static int max31790_write_fan(struct device *dev, u32 attr, int channel,
> > > struct i2c_client *client = data->client;
> > > int target_count;
> > > int err = 0;
> > > - u8 bits;
> > > + u8 bits, fan_config;
> > > int sr;
> > >
> > > mutex_lock(&data->update_lock);
> > > @@ -243,6 +252,23 @@ static int max31790_write_fan(struct device *dev, u32 attr, int channel,
> > > MAX31790_REG_TARGET_COUNT(channel),
> > > data->target_count[channel]);
> > > break;
> > > + case hwmon_fan_enable:
> > > + fan_config = data->fan_config[channel];
> > > + if (val == 0) {
> > > + fan_config &= ~MAX31790_FAN_CFG_TACH_INPUT_EN;
> > > + } else if (val == 1) {
> > > + fan_config |= MAX31790_FAN_CFG_TACH_INPUT_EN;
> > > + } else {
> > > + err = -EINVAL;
> > > + break;
> > > + }
> > > + if (fan_config != data->fan_config[channel]) {
> > > + err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
> > > + fan_config);
> > > + if (!err)
> > > + data->fan_config[channel] = fan_config;
> > > + }
> > > + break;
> > > default:
> > > err = -EOPNOTSUPP;
> > > break;
> > > @@ -270,6 +296,10 @@ static umode_t max31790_fan_is_visible(const void *_data, u32 attr, int channel)
> > > !(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
> > > return 0644;
> > > return 0;
> > > + case hwmon_fan_enable:
> > > + if (channel < NR_CHANNEL)
> > > + return 0644;
> > > + return 0;
> > > default:
> > > return 0;
> > > }
> > > @@ -423,12 +453,12 @@ static umode_t max31790_is_visible(const void *data,
> > >
> > > static const struct hwmon_channel_info *max31790_info[] = {
> > > HWMON_CHANNEL_INFO(fan,
> > > - HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> > > - HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> > > - HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> > > - HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> > > - HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> > > - HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
> > > + HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> > > + HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> > > + HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> > > + HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> > > + HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> > > + HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
> > > HWMON_F_INPUT | HWMON_F_FAULT,
> > > HWMON_F_INPUT | HWMON_F_FAULT,
> > > HWMON_F_INPUT | HWMON_F_FAULT,
> > > --
> > > 2.37.2.672.g94769d06f0-goog
> > >