Fix some typo in pwm and mdadm page

docs/mdadm.md

@@ -282,7 +282,7 @@ Once you have identified the failed drive with the command **mdadm -D**, as show
 
 5. Power-up your Helios4.
 
-6. Add the new drive to the array. You will need to use **lsblk** command to figure out what the device name of the new drive. Most probably it will be the same than before.
+6. Add the new drive to the array. You will need to use **lsblk** command to figure out what's the device name of the new drive. Most probably it will be the same than before.
 
     `sudo mdadm /dev/md0 --add /dev/sdc`
 
@@ -314,7 +314,7 @@ In order to get notified or to see visual indication that something is wrong wit
 
 ### Configure Email Alerts
 
-Receive a notification whenever mdadm detects something wrong with your array. This is very important since you don't want to miss out an issue on your array and have time to take the right actions.
+Receive a notification whenever mdadm detects something wrong with your array. This is very important since you don't want to miss out an issue on your array in order to have time to take the right actions.
 
     sudo nano /etc/mdadm/mdadm.conf
 
@@ -344,11 +344,11 @@ You can test your error notification setup by doing the following:
 
 ## Import an Existing RAID Array
 
-If for some reasons you want to add an existing array to your system (e.g you just did a new install of your operating system), you can use the following command to detect your existing array.
+If for some reasons you want to add an existing array to your system (e.g you just did a new fresh install of your operating system), you can use the following command to detect your existing array.
 
     sudo mdadm —assemble —scan
 
-Then refer to previous sections to mount the file system of this existing array and save its layout in mdadm configuration.
+Then refer to previous sections to mount the file system and save its layout in mdadm configuration.
 
 ## Reset Existing RAID Devices
 

docs/pwm.md

@@ -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)