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Linux/AM5728: Disabling pinmux override in kernel

ranchu
Guru 20755 points
Part Number: AM5728


Tool/software: Linux

Hello,

I would please like to ask about pinmux of AM572x.

We prefer to use pinmux only in u-boot, so that the same pinmux configuration will not be overriden in Linux.

Is that possible ?

Thank you,

Ran

  • 0
    TI__Guru**** 170625 points
    Hi Ran,

    Yes, that is possible.

    In fact, only MMC pinmux is done in kernel, everything else is done in u-boot-spl, check below e2e post:

    e2e.ti.com/.../2415822

    Regards,
    Pavel
  • 0 in reply to Pavel Botev
    Guru 20755 points
    Thank you Pavel,
    I would just like to ask the following please:

    1. Isn't changing pinmux for mmc in kernel a problem (concerning the "i869 IO Glitches Can Occur When Changing IO Settings" errata) ?

    2. I see in the given link that board file is used (board.c), but doesn't latest release for am572x use device tree (and not board file) ? If it is device tree I assume that in devicetree we can find the modifications of pinmux for mmc , Right ?

    Why Is it that the pinmux for mmc is done in kernel (device tree) and not also in u-boot ?

    Thank you
  • 0 in reply to ranchu
    TI__Guru**** 170625 points

    ranchu said:
    1. Isn't changing pinmux for mmc in kernel a problem (concerning the "i869 IO Glitches Can Occur When Changing IO Settings" errata) ?

    No. MMC is a special case. Check below doc for details:

    ranchu said:
    2. I see in the given link that board file is used (board.c), but doesn't latest release for am572x use device tree (and not board file) ? If it is device tree I assume that in devicetree we can find the modifications of pinmux for mmc , Right ?

    The given link is for u-boot code base. We use mainly DTS file for pinmux, board file code is just addition to DTS.

    ranchu said:
    Why Is it that the pinmux for mmc is done in kernel (device tree) and not also in u-boot ?

    MMC pinmux is done in both u-boot and kernel.

    Regards,

    Pavel