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    SubjectRe: [RFC PATCH 0/3] UART slave device bus
    On Mon, Aug 22, 2016 at 12:02 PM, One Thousand Gnomes
    <gnomes@lxorguk.ukuu.org.uk> wrote:
    >> > I think there are two other valuable features provided by serio:
    >> >
    >> > - an existing set of drivers written to the API
    >> > - the implementation of the tty_ldisc
    >>
    >> True, though I'd expect little of the data flow part of it to be reused.
    >
    > Then your design is broken.

    I'm talking about serio, not my design which I already said the
    receive side at least needs work.

    The serio API for rx and tx is a single character at a time. I thought
    we agreed that's not sufficient for things like BT.

    >> - a child of the uart node
    >> - a reg property containing the line number if the parent has multiple
    >> uarts (I'd expect this to rarely be used).
    >
    > That surprises me as for current x86 platforms it would be the norm,
    > except that we use ACPI.

    Exactly, we're talking DT bindings here. Each port will be a separate
    node otherwise things like serial aliases and stdout-path won't work
    correctly. Compatible strings for 8250 uarts are for a single port.
    But if you had h/w such that it has common and per port registers then
    it may be a single node. I'm not aware of any example offhand (maybe
    PPC CPM). But it doesn't matter as reg can handle this case just fine
    if we need to.

    >> - baudrate and other line configuration (though I would expect the
    >> slave driver to know all this and set it w/o DT. Also, we already have
    >> a way to set baudrate in the parent node at least.)
    >> - other standard device properties for interrupt, gpios, regulators.
    >>
    >> Also to consider is whether muxing of multiple slaves is needed. It's
    >> not anything I've seen come up, but it's not hard to imagine. I think
    >> that can be considered later and shouldn't impact the initial binding
    >> or infrastructure.
    >
    > You can describe the child of the serial device as a mux and the children
    > of the mux as whatever so it comes out fine when you get to that point.

    Yes, that's what I had in mind.

    Rob

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