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    SubjectRe: [PATCH] devicetree - document using aliases to set spi bus number.
    On Wed, May 25, 2016 at 08:25:44AM -0700, Frank Rowand wrote:
    > On 5/24/2016 10:41 AM, Mark Rutland wrote:
    > > On Tue, May 24, 2016 at 06:39:20PM +0200, Christer Weinigel wrote:
    > >> +Normally SPI buses are assigned dynamic bus numbers starting at 32766
    > >> +and counting downwards. It is possible to assign the bus number
    > >> +statically using devicetee aliases. For example, on the MPC5200 the
    > >> +"spi@f00" device above is connected to the "soc" bus. To set its
    > >> +bus_num to 1 add an aliases entry like this:
    > >
    > > As Mark Brown pointed out, this is very Linux-specific (at least in the
    > > wording of the above).
    > >
    > > Generally, aliases are there to match _physical_ identifiers (e.g. to
    > > match physical labels for UART0, UART1, and on).
    >
    > Can you point to anything in the specification or any other place that
    > states that aliases are for matching physical identifiers?
    >
    > Can you point to anything in the specification or any other place that
    > states that aliases are not to be used for anything else?

    You have me there; I cannot find any wording to that effect, and I am
    evidently going by my understanding alone.

    IEEE 1275 simply states that there may be predefined aliases for a
    machine, or that users can create and use them dynamically. ePAPR (and
    the devicetree specification) only states that aliases exist, and that a
    client program might use them (through some means which is never
    described).

    Thanks,
    Mark.

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