PHYTEC
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target$ cat /sys/class/backlight/backlight1/max_brightness
which will result in:
7
Valid brightness values are 0 to <max_brightness>.
To obtain the current brightness level, type:
target$ cat /sys/class/backlight/backlight1/brightness
you will get for example:
6
Write to the file
to change the brightness:
brightness
target$ echo 0 > /sys/class/backlight/backlight1/brightness
turns the backlight off,
target$ echo 6 > /sys/class/backlight/backlight1/brightness
sets the brightness to the second-highest brightness level. For documentation of all files, see
https://www.kernel.org/doc/Documentation/ABI/stable/sysfs-
Power Management
CPU Core Management
The i.MX 8M Plus SoC can have multiple processor cores on the die. The i.MX 8M Plus Quad, for example, has 4 ARM Cores which can be turned on and
off individually at runtime.
To see all available cores in the system, execute:
target$ ls /sys/devices/system/cpu -1
This will show, for example:
cpu0 cpu1 cpu2 cpu3 cpufreq
[...]
Here the system has four processor cores. By default, all available cores in the system are enabled to get maximum performance.
To switch off a single-core, execute:
target$ echo 0 > /sys/devices/system/cpu/cpu3/online
As confirmation, you will see:
[ 110.502295] CPU3: shutdown
[ 110.505012] psci: CPU3 killed.
Now the core is powered down and no more processes are scheduled on this core.
