dbroqua/kobol-wiki
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Fix some typo in pwm and mdadm page

Browse source
This commit is contained in:
Gauthier Provost 2018-11-14 14:35:03 +08:00
parent 4ca5fbaa65
commit 06ebc3f464
16 changed files with 41 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

63
docs/pwm.md
View file

@ -7,25 +7,25 @@ PWM, or pulse width modulation is a technique which allows us to adjust the aver
The term *duty cycle* describes the proportion of 'on' time to the regular interval or 'period' of time; a low duty cycle corresponds to low power, because the power is off for most of the time. Duty cycle is expressed in percent, 100% being fully on. When a digital signal is on half of the time and off the other half of the time, the digital signal has a duty cycle of 50% and resembles a "square" wave. When a digital signal spends more time in the on state than the off state, it has a duty cycle of >50%. When a digital signal spends more time in the off state than the on state, it has a duty cycle of <50%. Here is a pictorial that illustrates these three scenarios:
![PWM duty cycle](/img/hardware/pwm_duty_cycle_graph.png)
![PWM duty cycle](/img/pwm/pwm_duty_cycle_graph.png)
## PWM Fan Implementation
### Type A
![Type A Curve](/img/hardware/fan_type_a_curve.jpg)
![Type A Curve](/img/pwm/fan_type_a_curve.jpg)
### Type B
![Type B Curve](/img/hardware/fan_type_b_curve.jpg)
![Type B Curve](/img/pwm/fan_type_b_curve.jpg)
### Type C
![Type C Curve](/img/hardware/fan_type_c_curve.jpg)
![Type C Curve](/img/pwm/fan_type_c_curve.jpg)
## Helios4 Fan Control Schematic
![Helios4 Fan control](/img/hardware/fan_control_schematic.png)
![Helios4 Fan control](/img/pwm/fan_control_schematic.png)
| Description | Connector J10 | J17 | Remarks |
@ -36,7 +36,7 @@ The term *duty cycle* describes the proportion of 'on' time to the regular inter
## Bundled Fan
![Fan Connector](/img/hardware/fan_connector.png)
![Fan Connector](/img/pwm/fan_connector.png)
Connector Pinout
@ -50,7 +50,7 @@ Connector Pinout
### Old Fan (Batch 1)
![Old Fan](/img/hardware/fan_old_photo.jpg)
![Old Fan](/img/pwm/fan_old_photo.jpg)
Fan Specification
@ -61,14 +61,14 @@ Fan Specification
| Shut off | No | | Not Supported |
| Implementation Type | A | | |
![Old Fan Speed Graph](/img/hardware/fan_speed_graph_old_fan.png)
![Old Fan Speed Graph](/img/pwm/fan_speed_graph_old_fan.png)
!!! info
Duty cycle data is converted from Linux PWM
### New Fan (Batch 2)
![New Fan](/img/hardware/fan_new_photo.jpg)
![New Fan](/img/pwm/fan_new_photo.jpg)
Fan Specification
@ -79,14 +79,14 @@ Fan Specification
| Shut off | Yes | | duty cycle <= 5.5% and restart @ duty cycle > 9% |
| Implementation Type | C | | |
![New Fan Speed Graph](/img/hardware/fan_speed_graph_new_fan.png)
![New Fan Speed Graph](/img/pwm/fan_speed_graph_new_fan.png)
!!! info
Duty cycle data is converted from Linux PWM
### Fan Speed Comparison
![Fan Speed Graph](/img/hardware/fan_speed_comparison.png)
![Fan Speed Graph](/img/pwm/fan_speed_comparison.png)
## Helios4 Temperature Sensors
@ -108,15 +108,18 @@ Helios4 has a **Digital Temperature Sensor with 2‐wire Interface** ([NCT75 Dat
Linux use 8-bit integer to represent duty cycle. PWM value 0 represent 0% duty cycle and PWM value 255 represent 100% duty cycle.
![Duty Cycle Formula](/img/hardware/fan_duty_cycle_formula.png)
![Duty Cycle Formula](/img/pwm/fan_duty_cycle_formula.png)
Below graphs are bundled fan speed vs pwm value instead of duty cycle.
![Old Fan Speed Graph](/img/hardware/fan_speed_graph_old_fan_linux.png)
![Old Fan Speed Graph](/img/pwm/fan_speed_graph_old_fan_linux.png)
![New Fan Speed Graph](/img/hardware/fan_speed_graph_new_fan_linux.png)
![New Fan Speed Graph](/img/pwm/fan_speed_graph_new_fan_linux.png)
Currently Linux gpio-mvebu driver does not allow more than 1 PWM under the same bank. Helios4 uses 2 PWM under same bank therefore [this patch](https://raw.githubusercontent.com/armbian/build/master/patch/kernel/mvebu-next/92-mvebu-gpio-remove-hardcoded-timer-assignment.patch) needs to be applied to kernel source to remove the restriction.
### Patch requirement
Currently Linux gpio-mvebu driver does not allow more than 1 PWM under the same gpio bank. Helios4 uses 2 PWM under same bank therefore [this patch](https://raw.githubusercontent.com/armbian/build/master/patch/kernel/mvebu-next/92-mvebu-gpio-remove-hardcoded-timer-assignment.patch) needs to be applied to kernel source to remove the restriction.
### Using SYSFS interface
@ -156,11 +159,20 @@ echo NEW_PWM_VALUE > /sys/class/hwmon2/pwm1
echo NEW_PWM_VALUE > /sys/class/hwmon3/pwm1
```
### Fancontrol - automated software based fan speed regulation
### Fancontrol - automated software based fan speed control
fancontrol is a shell script for use with lm_sensors. It reads its configuration from a file, then calculates fan speeds from temperatures and sets the corresponding PWM outputs to the computed values.
fancontrol include *pwmconfig* script to create a configuration file but it can not be used in Helios4.
```
sudo apt-get install fancontrol
```
fancontrol includes *pwmconfig* script to create automatically a configuration file but it can not be used for Helios4.
#### UDEV rules
Since hwmon order can be changed between kernel version or even between reboot, on Armbian we use udev rules as workaround. The rules can be found from [here](https://raw.githubusercontent.com/armbian/build/master/packages/bsp/helios4/90-helios4-hwmon.rules) and to be copy to **/etc/udev/rules.d/**
#### Configuration File
@ -182,7 +194,7 @@ MINPWM=0
INTERVAL
This variable defines at which interval in seconds the main loop of fancontrol will be executed
This variable defines at which interval in seconds the main loop of fancontrol will be executed.
DEVPATH
@ -236,15 +248,18 @@ The PWM value to use when the temperature is below MINTEMP. Typically, this will
Set minimum PWM value to **0**. On new bundled fan, it would stopped the fan while on old bundled fan it would run in minimal speed.
!!! note
Since hwmon order can be changed between kernel version or even between reboot, on Armbian we use udev rules as workaround. The rules can be found from [here](https://raw.githubusercontent.com/armbian/build/master/packages/bsp/helios4/90-helios4-hwmon.rules) and the configuration file can be found [here](https://raw.githubusercontent.com/armbian/build/master/packages/bsp/helios4/fancontrol_pwm-fan-mvebu-next.conf)
!!! note
The Helios4 fancontrol configuration file can be found [here](https://raw.githubusercontent.com/armbian/build/master/packages/bsp/helios4/fancontrol_pwm-fan-mvebu-next.conf).
### Thermal Zone on Device Tree
Linux provide Thermal Framework to do thermal management. By using this method to control the fan speed, no userspace such as [fancontrol](#fancontrol-automated-software-based-fan-speed-regulation) is required.
As an alternative to userspace tool like [fancontrol](#fancontrol-automated-software-based-fan-speed-regulation), Linux Kernel provides Thermal Framework to do thermal management.
Below are device tree nodes that can be added to Helios4 device tree to make use of Linux Thermal Framework.
Below is an example of device tree nodes that can be added to Helios4 device tree to make use of Linux Thermal Framework.
!!! note
Currently *armada_thermal* driver ([CPU Thermal Sensor](#cpu-thermal-sensor)) does not support thermal-zone binding in device tree, therefore it can not be used as thermal-sensor yet.
```
/ {
@ -346,10 +361,6 @@ Below are device tree nodes that can be added to Helios4 device tree to make use
};
```
!!! info
Currently *armada_thermal* driver ([CPU Thermal Sensor](#cpu-thermal-sensor)) does not support thermal-zone binding in device tree, therefore it can not be used as thermal-sensor.
## References
[Pulse-width modulation](https://en.wikipedia.org/wiki/Pulse-width_modulation)