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TDA4VM: overlay dtb files in u-boot

Mohsen Khayami
Mastermind 22391 points
Part Number: TDA4VM

Hi

trying to see what exactly needs to happen for the overlay dtb file to be used. It looks like you only have to set the below u-boot environment with the TI SDK and it will use the overlay dtb file. so for example 

setenv name_overlays k3-j721e-vision-apps.dtbo

saveenv

then it should use the overly file that is mentioned above. Also the dtbo should be in the /boot directory.

Is there anything else that needs to be set? The reason for the question is because of the highlighted text below. I am not sure where is the variable overlay is set? i assume it is set in u-boot but like to understand the details as to what is required for the overlays to be used.

get_overlay_mmc=fdt address ${fdtaddr};fdt resize 0x100000;for overlay in $name_overlays;do;load mmc ${bootpart} ${overlayaddr} ${bootdir}/${overlay};fdt apply ${overlayaddr};done;

Thanks

  • 0
    TI__Guru**** 163660 points

    Mohsen,

    uenv.txt has this line - name_overlays=k3-j721e-vision-apps.dtbo

    You can even do: setenv name_overlays k3-j721e-vision-apps.dtbo

    Like you have mentioned.

    For PSDKLA You can also see that getting set in u-boot: board/ti/j721e/evm.c

    Function: probe_daughtercards(void)

    /* Append to our list of overlays */
                strcat(name_overlays, ext_cards[i].dtbo_name);

    The above typically apends: {
    0x52,
    "J7X-INFOTAN-EXP",
    "k3-j721e-common-proc-board-infotainment.dtbo",
    0,
    },

    So if you boot PSDKLA to u-boot and try the below command:
    printenv name_overlays

    It prints "k3-j721e-common-proc-board-infotainment.dtbo".

    If no further questions please click on verify answer.

    - Keerthy

  • 0 in reply to Keerthy J
    TI__Mastermind 22391 points

    Hi Keerthy

    it does make sense, i guess i should have pay more attention to the for loop, it says 

    for overlay in $name_overlays;do;load mmc ${bootpart} ${overlayaddr} ${bootdir}/${overlay};fdt apply ${overlayaddr};done;

    so if there are any overlay dtbo files in the variable name_overlay   then do the below if not dont do anything.

    for overlay in $name_overlays

    do

    load mmc ${bootpart} ${overlayaddr} ${bootdir}/${overlay};

    fdt apply ${overlayaddr};

    done

     sorry i did not pay too much attention to what was going on.

    Thanks for the help