i.MX 93 BSP Manual PD24.1.1 Documentation Rev.: imx8mp-pd22.1.2-51-ga548be7d
target:~$ systemctl stop weston
Note
The Qt demo must be closed before Weston can be closed.
7.17.2 Backlight Control
If a display is connected to the PHYTEC board, you can control its backlight with the Linux kernel sysfs
interface. All available backlight devices in the system can be found in the folder /sys/class/backlight.
Reading the appropriate les and writing to them allows you to control the backlight.
Note
Some boards with multiple display connectors might have multiple backlight controls in
/sys/class/backlight. For example: backlight0 and backlight1
• To get, for example, the maximum brightness level (max_brightness) execute:
target:~$ cat /sys/class/backlight/backlight/max_brightness
Valid brightness values are 0 to <max_brightness>.
• To obtain the current brightness level, type:
target:~$ cat /sys/class/backlight/backlight/brightness
• Write to the le brightness to change the brightness:
target:~$ echo 0 > /sys/class/backlight/backlight/brightness
turns the backlight o for example.
For documentation of all les, see https://www.kernel.org/doc/Documentation/ABI/stable/
sysfs-class-backlight.
The device tree of PEB-AV-02 can be found here: https://git.phytec.de/linux-imx/tree/arch/arm64/boot/
dts/freescale/imx93-phyboard-segin-peb-av-02.dtso?h=v6.1.55_2.2.0-phy3
The device tree of PEB-AV-10 can be found here: https://git.phytec.de/linux-imx/tree/arch/arm64/boot/
dts/freescale/imx93-phyboard-nash-peb-av-010.dtso?h=v6.1.55_2.2.0-phy3
7.18 Power Management
7.18.1 CPU Core Frequency Scaling
The CPU in the i.MX 93 SoC is able to scale the clock frequency and the voltage. This is used to save power
when the full performance of the CPU is not needed. Unlike i.MX8 M family the i.MX 93 doesn’t support
Dynamic Voltage and Frequency Scaling (DVFS), but has the support of basic Voltage and Frequency
Scaling (VFS). The board can be put into these modes:
• nominal (ND),
• overdrive (OD),
Accessing Peripherals 71
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