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    SubjectRe: dmaengine.c: question about device_alloc_chan_resources
    "Dan Williams" <dan.j.williams@intel.com> wrote:
    > On Thu, Sep 18, 2008 at 7:45 AM, Haavard Skinnemoen
    > <haavard.skinnemoen@atmel.com> wrote:
    > > Timur Tabi <timur@freescale.com> wrote:
    > >> Haavard Skinnemoen wrote:
    > >>
    > >> > Wouldn't it be better if the dmaengine layer made sure it didn't pass
    > >> > the same channel several times to a client?
    > >>
    > >> Wouldn't that require it to keep track of which clients have already seen which
    > >> channels? It might make more sense, but it's probably easier the current way.
    > >
    > > I guess so. What would be even more simple is to simply prevent other
    > > clients from taking a channel once someone has acked it, which would be
    > > perfect for my purposes, but perhaps not everyone else's...
    >
    > Does not seem too bad to have something like a DMA_EXCL flag in
    > dma_chan to tell the core not to show this channel to any other
    > clients.

    Yes, or maybe provide an interface for simply requesting a channel
    without having to register any callbacks. With some drivers, the number
    of required channels is fixed, and not using DMA just isn't an option.
    A simple "get a channel which satisfies these constraints" interface
    would simplify these drivers a lot.

    Haavard


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