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Date:   Tue, 15 Sep 2020 17:51:04 +0200
From:   Christoph Hellwig <>
To:     Mauro Carvalho Chehab <>,
        Thomas Bogendoerfer <>,
        "James E.J. Bottomley" <>,
        Joonyoung Shim <>,
        Seung-Woo Kim <>,
        Ben Skeggs <>,
        Marek Szyprowski <>,
        Tomasz Figa <>,
        Matt Porter <>,
Cc:     Stefan Richter <>,,,,,,,,,,,,,
Subject: a saner API for allocating DMA addressable pages v3

Hi all,

this series replaced the DMA_ATTR_NON_CONSISTENT flag to dma_alloc_attrs
with a separate new dma_alloc_pages API, which is available on all
platforms.  In addition to cleaning up the convoluted code path, this
ensures that other drivers that have asked for better support for
non-coherent DMA to pages with incurring bounce buffering over can finally
be properly supported.

As a follow up I plan to move the implementation of the
DMA_ATTR_NO_KERNEL_MAPPING flag over to this framework as well, given
that is also is a fundamentally non coherent allocation.  The replacement
for that flag would then return a struct page, as it is allowed to
actually return pages without a kernel mapping as the name suggested
(although most of the time they will actually have a kernel mapping..)

In addition to the conversions of the existing non-coherent DMA users,
I've also added a patch to convert the firewire ohci driver to use
the new dma_alloc_pages API.

The first patch is queued up for 5.9 in the media tree, but included here
for completeness.

A git tree is available here:

    git:// dma_alloc_pages


Changes since v2:
 - fix up the patch reshuffle which wasn't quite correct
 - fix up a few commit messages

Changes since v1:
 - rebased on the latests dma-mapping tree, which merged many of the
 - fix an argument passing typo in 53c700, caught by sparse
 - rename a few macro arguments in 53c700
 - pass the right device to the DMA API in the lib82596 drivers
 - fix memory ownershiptransfers in sgiseeq
 - better document what a page in the direct kernel mapping means
 - split into dma_alloc_pages that returns a struct page and is in the
   direct mapping vs dma_alloc_noncoherent that can be vmapped
 - conver the firewire ohci driver to dma_alloc_pages


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