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    SubjectRe: [PATCH 2/2] DMAENGINE: driver for the ARM PL080/PL081 PrimeCells
    From
    2010/7/28 Dan Williams <dan.j.williams@intel.com>:
    > On Tue, Jun 29, 2010 at 4:36 AM, Linus Walleij
    > <linus.walleij@stericsson.com> wrote:
    >> This creates a DMAengine driver for the ARM PL080/PL081 PrimeCells
    >> based on the implementation earlier submitted by Peter Pearse.
    >> This is working like a charm for memcpy and slave DMA to the PL011
    >> PrimeCell on the PB11MPCore.
    >
    > Russell I am assuming this implementation and testing is sufficient to
    > allay your prior nak [1]?  Linus is oversubscribing virtual channels
    > to physical channels to handle muxing.

    I don't think Russell has ever NAK:ed the PL08x driver(s). The NAK
    was about the PrimeCell DMA extenstions to amba-pl011.c etc.
    (Still I'm happy if Russell looks at this thing of course.)

    This patch along with the generic channel control removed the
    cross-dependency between the PrimeCell DMA patchset and the
    drivers/dma DMA engine framework (yay!) so there is no arch/arm
    or AMBA stuff involved anymore, other than the fact that this driver
    sits on the AMBA/PrimeCell bus.

    >> +#ifdef MODULE
    >> +
    >> +# error "AMBA PL08X DMA CANNOT BE COMPILED AS A LOADABLE MODULE AT PRESENT"
    >> +
    >> +/*
    >> +       a) Some devices might make use of DMA during boot
    >> +          (esp true for DMAENGINE implementation)
    >> +       b) Memory allocation will need much more attention
    >> +          before load/unload can be supported
    >> + */
    >> +#endif
    >
    > This is taken care of by being "config bool", but I assume you want
    > this for documentation purposes?

    Peter had that in and I didn't remove it. If you don't like it you
    can remove it or I can send a new patch.

    >> +       txd = kzalloc(sizeof(struct pl08x_txd), GFP_KERNEL);
    >
    > ...appears in the prep routines.  Will this driver be used by any
    > storage controllers on the platfom?  Might we deadlock waiting on i/o
    > that needs to allocate a descriptor to complete?

    I haven't noticed anything but a descriptor pool is on my
    list of things to look into and fix.

    Yours,
    Linus Walleij
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