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Linux/TDA2SX: u-boot & kernel device tree porting

LiuGan
Expert 1285 points
Part Number: TDA2SX
Other Parts Discussed in Thread: TPS65090

Tool/software: Linux

Dear TI,

I am now trying to porting linux to my custom board and stucking in device tree porting.

Please help me with these questions.

uboot device tree:

question 1: Is it nessary to use devicetree in uboot? If not, how the periferals drivers be registered?

question 2: Which stage is the compiled dtb file being used in？(sbl, uboot)

question 3: I have tda2x evm at hand for now. I found it so hard to get my own dts file modify from dra7x-evm-vision.dts file.

                  Because there are so many devices , which are defined in the dtsi files, but not present on my board.

So which dts file should i reference to start my own dts file?

kernel device tree:

question 4: Are there any rules to organize the dtsi and dts files? i.e. Which devices should be placed in dtsi file?

Regards,

Liu Gan

  • 0
    TI__Genius 14650 points
    Hi Liu,

    Which version of Linux / U-boot are you using?

    1. Yes, DTBs need to be ported on both u-boot and kernel.
    2. The DTB file is used in the second stage boot loader (u-boot)
    3. Please use dra7-evm.dts as the reference device-tree. This device-tree is written for the base EVM board.
    4. dtsi files should have all the devices listed. DTS files includes dtsi files and modifies attributes for the devices defined in dtsi.

    Regards
    Shravan
  • 0 in reply to Shravan Karthik
    Expert 1285 points

    Hi Shravan

    Thanks for your reply.

    I am working with TI VSDK v3.6 and the corresponding kernel/u-boot release tags.

    Do i need to disable the devices descripted in the included dtsi files,  but are not uesed in my custom board if i take dra7-evm.dts as reference?

    dts snippet from dra7-evm.dts:

    What are these two nodes used for?

    What's more i can not find the min/max-microvolt definded here in the data manual of tps65903x. So i cannot decide how to modify or delete these nodes.

    Does TI have any released or traning docs/videos about the dts file ?

    Regards,

    Liu Gan

  • 0 in reply to LiuGan
    TI__Genius 14650 points
    Hi Liu,

    It is recommended you add the status = "disabled" attribute in the final dts file for devices you aren't using. For example if you're not using uart2, please add the below in your kernel device-tree

    &uart2 {
    status = "disabled";
    };

    The snippet in the above post lists the voltage regulators for MMC/SD card which is adjusted depending on the mode at which the sd card operates.

    If you're using the tps65903x PMIC, please refer to Documentation/devicetree/bindings/regulator/tps65090.txt for the device tree bindings.

    Regards
    Shravan