1. Article purpose[edit | edit source]
This article explains how to configure the VDEC [1] when the peripheral is assigned to the Linux® OS.
The configuration is performed using the device tree mechanism [2].
The Device tree provides a hardware description of the VDEC [1] used by the STM32 VDEC Linux driver.
2. DT bindings documentation[edit | edit source]
The VDEC is represented by the STM32 VDEC device tree bindings file: st,stm32mp25-video-codec.yaml .
3. DT configuration[edit | edit source]
This hardware description is a combination of the STM32 microprocessor device tree files (.dtsi extension) and board device tree files (.dts extension). See the Device tree for an explanation of the device tree file split.
STM32CubeMX can be used to generate the board device tree. Refer to How to configure the DT using STM32CubeMX for more details.
3.1. DT configuration (STM32/SoC level)[edit | edit source]
The VDEC node is located in the device tree file for the software components, supporting the peripheral and listed in the above DT bindings documentation paragraph.
The VDEC device tree node is declared in:
- arch/arm64/boot/dts/st/stm32mp235.dtsi on STM32MP23x lines
...
&rifsc {
...
vdec: vdec@480d0000 {
compatible = "st,stm32mp25-vdec";
reg = <0x480d0000 0x3c8>;
resets = <&rcc VDEC_R>;
interrupts = <GIC_SPI 117 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&rcc CK_BUS_VDEC>;
access-controllers = <&rifsc 89>;
power-domains = <&CLUSTER_PD>;
};
...
- arch/arm64/boot/dts/st/stm32mp255.dtsi on STM32MP25x lines
...
&rifsc {
...
vdec: vdec@480d0000 {
compatible = "st,stm32mp25-vdec";
reg = <0x480d0000 0x3c8>;
resets = <&rcc VDEC_R>;
interrupts = <GIC_SPI 117 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&rcc CK_BUS_VDEC>;
access-controllers = <&rifsc 89>;
power-domains = <&CLUSTER_PD>;
};
...
3.2. DT configuration (board level)[edit | edit source]
For STM32MP23x lines and STM32MP25x lines , the STM32 VDEC is already enabled by default in stm32mp235.dtsi and stm32mp255.dtsi , so there is no need to enable it at board level.
4. How to configure the DT using STM32CubeMX[edit | edit source]
The STM32CubeMX tool can be used to configure the STM32MPU device and get the corresponding platform configuration device tree files.
The STM32CubeMX may not support all the properties described in the above DT bindings documentation paragraph. If so, the tool inserts user sections in the generated device tree. These sections can then be edited to add some properties and they are preserved from one generation to another. Refer to STM32CubeMX user manual for further information.
5. References[edit | edit source]
Please refer to the following links for additional information: