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    SubjectRe: [PATCH v5 4/7] drivers: dma-coherent: Introduce default DMA pool
    On Tue, Jun 27, 2017 at 03:36:16PM +0100, Robin Murphy wrote:
    > I admit I'm almost in agreement, were it not for the fact that
    > dma-contiguous already supports all four combinations of both per-device
    > and global pools, and both reserved mem and direct declarations from
    > arch/platform code, all through the same interface to boot, and nobody's
    > complaining about that. The only real difference for dma-coherent seems
    > to be the way it's baked into the existing API.
    >
    > If it is just a matter of interfaces, I'd have no objection to exporting
    > a separate e.g. dma_alloc_from_global_coherent() or somesuch as a
    > conceptually separate interface to dma_coherent_default_memory, which
    > the arch code can then call from ->alloc in the same manner they
    > currently call dma_alloc_from_contiguous(). That seems like a reasonable
    > way to keep the per-device and global pools conceptually distinct
    > without needlessly duplicating implementations. In fact, I'm now
    > wondering if the regular arm/arm64 atomic pools couldn't also make use
    > of such a thing as well...

    Ok. I think I'll just go ahead with the current patches, and then
    we'll try to come up with something better later. I really don't
    want it in actual arch code, but I want it controlled from the
    dma_map_ops instance instead of from generic code. There will be
    a lot of churn in this area if my plans go ahead, so I think we can
    handle it then.

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