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From: Christoph Hellwig <hch@lst.de>
To: Mauro Carvalho Chehab <mchehab@kernel.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Tomasz Figa <tfiga@chromium.org>,
	iommu@lists.linux-foundation.org
Cc: Robin Murphy <robin.murphy@arm.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-media@vger.kernel.org
Subject: dma_alloc_pages / dma_alloc_noncoherent fixups
Date: Wed, 30 Sep 2020 18:09:09 +0200	[thread overview]
Message-ID: <20200930160917.1234225-1-hch@lst.de> (raw)

Hi all,

this series has a bunch of fixups for the noncoherent DMA allocator
rework that recently landed in linux-next.

I think the most important part is that the idea of vmap()ing
non-contiguous allocations in dma_alloc_noncoherent doesn't work very
well after all.  It means we can't just rely on virt_to_page to get
the page and just use remap_pfn_range or stuff it into other APIs,
but on the other hand it also isn't really generic enought for what
the media APIs seems to want.

So the first patch reverts that change, and the last patch suggests
a different lower level API which should allow the media code to do
all it wants.

I'd suggest all but the last patch for the current merge window, and
we should have a discussion on how well the last one suits the media
subsystem, and probably merge it together with any media changes to
use the required API.

             reply	other threads:[~2020-09-30 16:10 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-30 16:09 Christoph Hellwig [this message]
2020-09-30 16:09 ` [PATCH 1/8] dma-mapping: remove the {alloc,free}_noncoherent methods Christoph Hellwig
2020-09-30 16:09 ` [PATCH 2/8] dma-mapping: document dma_{alloc,free}_pages Christoph Hellwig
2020-09-30 16:09 ` [PATCH 3/8] dma-direct check for highmem pages in dma_direct_alloc_pages Christoph Hellwig
2020-09-30 16:09 ` [PATCH 4/8] dma-direct: use __GFP_ZERO " Christoph Hellwig
2020-09-30 16:09 ` [PATCH 5/8] dma-direct: factor out a dma_direct_alloc_from_pool helper Christoph Hellwig
2020-09-30 16:09 ` [PATCH 6/8] dma-direct: simplify the DMA_ATTR_NO_KERNEL_MAPPING handling Christoph Hellwig
2020-09-30 16:09 ` [PATCH 7/8] dma-iommu: remove __iommu_dma_mmap Christoph Hellwig
2020-09-30 16:09 ` [PATCH 8/8] WIP: add a dma_alloc_contiguous API Christoph Hellwig
2020-10-02 17:50   ` Tomasz Figa
2020-10-05  8:26     ` Christoph Hellwig
2020-10-06 20:56       ` Tomasz Figa
2020-10-07  6:21         ` Christoph Hellwig
2020-10-07 12:21           ` Tomasz Figa
2020-10-07 12:24             ` Christoph Hellwig
2020-10-14 13:20   ` Tomasz Figa
2020-10-14 15:03     ` David Laight
2020-11-09 14:53     ` Ricardo Ribalda
2020-11-10  9:25       ` Christoph Hellwig
2020-11-10  9:33         ` Ricardo Ribalda
2020-11-10  9:41           ` Christoph Hellwig
2020-11-10  9:50           ` Tomasz Figa
2020-11-10  9:57             ` Christoph Hellwig
2020-11-17 21:21               ` Ricardo Ribalda
2020-11-18 14:25   ` [PATCH] WIP! media: uvcvideo: Use dma_alloc_noncontiguos API Ricardo Ribalda
2020-11-24 11:35     ` Christoph Hellwig
2020-11-24 12:01       ` Ricardo Ribalda
2020-11-24 13:33         ` Christoph Hellwig

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