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    SubjectRe: [PATCH v12 0/6] Driver for at91 usart in spi mode
    On 12/09/2018 12:43:52+0100, Lee Jones wrote:
    > > > But ... we can't have it both ways. *Either* it's a true MFD, in
    > > > which case it can/should have 2 separate compatible strings which can
    > > > be specified directly from the DT. *Or* it's not an MFD. In the
    > > > latter case, which I think we're all agreeing on (else we'd have 2
    > > > compatible strings), MFD is not the place to handle this (my original
    > > > point).
    > > >
    > >
    > > If that is what bothers you, then let's move it out of mfd.
    >
    > As I've already mentioned. I don't just want it moved out of MFD and
    > shoved somewhere else. My aim is to fix this properly.
    >

    If it is out of MFD, then I'm not sure why you would care too much about
    it as you won't be maintaining that code. And I still this what was done
    was correct but I'm open to test what you suggest.

    > > > So ... this is a USART device which can do SPI, right?
    > > >
    > > > My current thinking is that; as this is a USART device first &
    > > > foremost, the USART should be probed in the first instance regardless,
    > > > then if SPI mode is specified it (the USART driver) registers the SPI
    > > > platform driver (as MFD does currently) and exits gracefully, allowing
    > > > the SPI driver to take over.
    > > >
    > > > Spanner in the works: is it physically possible to change the mode at
    > > > run-time? :s
    > >
    > > Yes it is possible but on Linux that will not happen without probing
    > > the drivers again.
    >
    > Not sure I understand what you mean.
    >

    I was just commenting on changing the mode at runtime.

    > I'm suggesting that you use the same platform_* interfaces MFD uses to
    > register the SPI driver if SPI mode has been selected. Only do so
    > from the appropriate driver i.e. USART.
    >

    Yeah, I understood that but I didn't comment because I'm not sure this
    will work yet.

    --
    Alexandre Belloni, Bootlin
    Embedded Linux and Kernel engineering
    https://bootlin.com

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