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    SubjectRe: [PATCH 2/2] fpga: add FPGA manager debugfs
    Hi Federico,

    On Thu, Aug 16, 2018 at 11:21:32PM +0200, Federico Vaga wrote:
    > Hi,
    >
    > On Thursday, August 16, 2018 10:04:51 PM CEST Alan Tull wrote:
    > > On Thu, Aug 16, 2018 at 1:59 PM, Moritz Fischer <mdf@kernel.org> wrote:
    > > > Hi Alan,
    > >
    > > Hi Moritz,
    > >
    > > > comments inline. While I see how this is useful, I have the
    > > > suspicion that from the moment this gets merged vendor kernels
    > > > will just default to use this ...
    > >
    > > Yeah, I have that suspicion as well. That's probably why I sat on
    > > this and didn't upstream it for 2 years. But on the other hand, I
    > > keep hearing of lots of cases of people implementing this
    > > independently anyway. At least if it is debugfs, it makes it clear
    > > that it's not intended for production use.
    >
    > I'm one of those guys who implemented this independently.

    We all have in one way or another ;) Most people on ARM run an out of tree
    patch using devicetree overlays these days I hope rather than /dev/mem
    and UIO ... or other vender solutions...
    >
    > @Mortiz
    > I do not see how this can be a bad thing (from what you wrote I guess you
    > prefer another interface). Which interface to use depends on the use case.
    > If you have this suspicion it's, I guess, because such interface it is
    > extremely easy to use.

    What happens to a kernel driver doing MMIO with devices while you reload
    the entire FPGA from userland?
    >
    > @Alan
    > DebugFS can be a first step, but I would go for a normal device in /dev at
    > some point. I do not see why this should not be used in production

    I'm not against having a userland interface to reprogram the FPGA, the
    Intel DFL code is a good example of a sensible one, doing so in a safe
    manner.

    Ideally we'll get around to have a more generic interface, as we get
    time to work on it.

    - Moritz

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