Re: [PATCH 2/3] hwmon: (adt7475) fan stall prevention

From: Guenter Roeck
Date: Tue May 02 2017 - 14:07:49 EST

On Tue, May 02, 2017 at 05:45:35PM +1200, Chris Packham wrote:
> By default adt7475 will stop the fans (pwm duty cycle 0%) when the
> temperature drops past Tmin - hysteresis. Some systems want to keep the
> fans moving even when the temperature drops so add new sysfs attributes
> that configure the enhanced acoustics min 1-3 which allows the fans to
> run at the minimum configure pwm duty cycle.
>
> Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
> ---
> pwmN_min is a horrible name but I really can't think of anything better.
> I'm biased a little because that is essentially the name of the bits in
> the datasheet. I'm open to suggestions.

pwmX_min is also traditionally the mimimum permitted pwm value,
not a boolean. This would be more appropriate to reflect the PWMmin
register values (0x64 to 0x66). Similar for pwmX_max if you want to
add support for it.
It might make sense to combine pwmX_min==0 with clearing the
respective bit in the REG_ENHANCE_ACOUSTICS[12] register. This way
we would only need one attribute to support both.

Guenter

>
> Documentation/hwmon/adt7475 | 5 +++++
> drivers/hwmon/adt7475.c | 50 +++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 55 insertions(+)
>
> diff --git a/Documentation/hwmon/adt7475 b/Documentation/hwmon/adt7475
> index 0502f2b464e1..85dc9e17bdee 100644
> --- a/Documentation/hwmon/adt7475
> +++ b/Documentation/hwmon/adt7475
> @@ -109,6 +109,11 @@ fan speed) is applied. PWM values range from 0 (off) to 255 (full speed).
> Fan speed may be set to maximum when the temperature sensor associated with
> the PWM control exceeds temp#_max.
>
> +At Tmin - hysteresis the PWM output can either be off (0% duty cycle) or
> +at the minimum (i.e. auto_point1_pwm). This can be configured using the
> +pwm[1-*]_min sysfs attribute. A value of 0 means the fans will shut off. A
> +value of 1 means the fans will run at auto_point1_pwm.
> +
> Notes
> -----
>
> diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
> index ec0c43fbcdce..53f25bda0919 100644
> --- a/drivers/hwmon/adt7475.c
> +++ b/drivers/hwmon/adt7475.c
> @@ -79,6 +79,9 @@
>
> #define REG_TEMP_TRANGE_BASE 0x5F
>
> +#define REG_ENHANCE_ACOUSTICS1 0x62
> +#define REG_ENHANCE_ACOUSTICS2 0x63
> +
> #define REG_PWM_MIN_BASE 0x64
>
> #define REG_TEMP_TMIN_BASE 0x67
> @@ -209,6 +212,7 @@ struct adt7475_data {
> u8 range[3];
> u8 pwmctl[3];
> u8 pwmchan[3];
> + u8 enh_acou[2];
>
> u8 vid;
> u8 vrm;
> @@ -700,6 +704,43 @@ static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
> data->pwm[sattr->nr][sattr->index] = clamp_val(val, 0, 0xFF);
> i2c_smbus_write_byte_data(client, reg,
> data->pwm[sattr->nr][sattr->index]);
> + mutex_unlock(&data->lock);
> +
> + return count;
> +}
> +
> +
> +static ssize_t show_pwm_min(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
> + struct i2c_client *client = to_i2c_client(dev);
> + struct adt7475_data *data = i2c_get_clientdata(client);
> + u8 mask = BIT(5 + sattr->index);
> +
> + return sprintf(buf, "%d\n", !!(data->enh_acou[0] & mask));
> +}
> +
> +static ssize_t set_pwm_min(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
> + struct i2c_client *client = to_i2c_client(dev);
> + struct adt7475_data *data = i2c_get_clientdata(client);
> + long val;
> + u8 mask = BIT(5 + sattr->index);
> +
> + if (kstrtol(buf, 10, &val))
> + return -EINVAL;
> +
> + mutex_lock(&data->lock);
> +
> + data->enh_acou[0] &= ~mask;
> + if (val)
> + data->enh_acou[0] |= mask;
> +
> + i2c_smbus_write_byte_data(client, REG_ENHANCE_ACOUSTICS1,
> + data->enh_acou[0]);
>
> mutex_unlock(&data->lock);
>
> @@ -1028,6 +1069,8 @@ static SENSOR_DEVICE_ATTR_2(pwm1_auto_point1_pwm, S_IRUGO | S_IWUSR, show_pwm,
> set_pwm, MIN, 0);
> static SENSOR_DEVICE_ATTR_2(pwm1_auto_point2_pwm, S_IRUGO | S_IWUSR, show_pwm,
> set_pwm, MAX, 0);
> +static SENSOR_DEVICE_ATTR_2(pwm1_min, S_IRUGO | S_IWUSR, show_pwm_min,
> + set_pwm_min, 0, 0);
> static SENSOR_DEVICE_ATTR_2(pwm2, S_IRUGO | S_IWUSR, show_pwm, set_pwm, INPUT,
> 1);
> static SENSOR_DEVICE_ATTR_2(pwm2_freq, S_IRUGO | S_IWUSR, show_pwmfreq,
> @@ -1040,6 +1083,8 @@ static SENSOR_DEVICE_ATTR_2(pwm2_auto_point1_pwm, S_IRUGO | S_IWUSR, show_pwm,
> set_pwm, MIN, 1);
> static SENSOR_DEVICE_ATTR_2(pwm2_auto_point2_pwm, S_IRUGO | S_IWUSR, show_pwm,
> set_pwm, MAX, 1);
> +static SENSOR_DEVICE_ATTR_2(pwm2_min, S_IRUGO | S_IWUSR, show_pwm_min,
> + set_pwm_min, 0, 1);
> static SENSOR_DEVICE_ATTR_2(pwm3, S_IRUGO | S_IWUSR, show_pwm, set_pwm, INPUT,
> 2);
> static SENSOR_DEVICE_ATTR_2(pwm3_freq, S_IRUGO | S_IWUSR, show_pwmfreq,
> @@ -1052,6 +1097,8 @@ static SENSOR_DEVICE_ATTR_2(pwm3_auto_point1_pwm, S_IRUGO | S_IWUSR, show_pwm,
> set_pwm, MIN, 2);
> static SENSOR_DEVICE_ATTR_2(pwm3_auto_point2_pwm, S_IRUGO | S_IWUSR, show_pwm,
> set_pwm, MAX, 2);
> +static SENSOR_DEVICE_ATTR_2(pwm3_min, S_IRUGO | S_IWUSR, show_pwm_min,
> + set_pwm_min, 0, 2);
>
> /* Non-standard name, might need revisiting */
> static DEVICE_ATTR_RW(pwm_use_point2_pwm_at_crit);
> @@ -1112,12 +1159,14 @@ static struct attribute *adt7475_attrs[] = {
> &sensor_dev_attr_pwm1_auto_channels_temp.dev_attr.attr,
> &sensor_dev_attr_pwm1_auto_point1_pwm.dev_attr.attr,
> &sensor_dev_attr_pwm1_auto_point2_pwm.dev_attr.attr,
> + &sensor_dev_attr_pwm1_min.dev_attr.attr,
> &sensor_dev_attr_pwm3.dev_attr.attr,
> &sensor_dev_attr_pwm3_freq.dev_attr.attr,
> &sensor_dev_attr_pwm3_enable.dev_attr.attr,
> &sensor_dev_attr_pwm3_auto_channels_temp.dev_attr.attr,
> &sensor_dev_attr_pwm3_auto_point1_pwm.dev_attr.attr,
> &sensor_dev_attr_pwm3_auto_point2_pwm.dev_attr.attr,
> + &sensor_dev_attr_pwm3_min.dev_attr.attr,
> &dev_attr_pwm_use_point2_pwm_at_crit.attr,
> NULL,
> };
> @@ -1136,6 +1185,7 @@ static struct attribute *pwm2_attrs[] = {
> &sensor_dev_attr_pwm2_auto_channels_temp.dev_attr.attr,
> &sensor_dev_attr_pwm2_auto_point1_pwm.dev_attr.attr,
> &sensor_dev_attr_pwm2_auto_point2_pwm.dev_attr.attr,
> + &sensor_dev_attr_pwm2_min.dev_attr.attr,
> NULL
> };
>
> --
> 2.11.0.24.ge6920cf
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html