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From: Christoph Hellwig <hch@lst.de>
To: iommu@lists.linux-foundation.org,
	Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Takashi Iwai <tiwai@suse.de>, Robin Murphy <robin.murphy@arm.com>,
	Michal Simek <monstr@monstr.eu>,
	linux-arm-kernel@lists.infradead.org,
	linux-m68k@lists.linux-m68k.org, linux-parisc@vger.kernel.org,
	linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org,
	linuxppc-dev@lists.ozlabs.org, x86@kernel.org,
	linux-kernel@vger.kernel.org
Subject: remove default fallbacks in dma_map_ops v2
Date: Mon,  5 Aug 2019 12:11:52 +0300
Message-ID: <20190805091159.7826-1-hch@lst.de> (raw)

Hi all,

we have a few places where the DMA mapping layer has non-trivial default
actions that are questionable and/or dangerous.

This series instead wires up the mmap, get_sgtable and get_required_mask
methods explicitly and cleans up some surrounding areas.  This also means
we could get rid of the ARCH_NO_COHERENT_DMA_MMAP kconfig option, as we
now require a mmap method wired up, or in case of non-coherent dma-direct
the presence of the arch_dma_coherent_to_pfn hook.  The only interesting
case is that the sound code also checked the ARCH_NO_COHERENT_DMA_MMAP
symbol in somewhat odd ways, so I'd like to see a review of the sound
situation before going forward with that patch.

Changes since v1:
 - add a dma_can_mmap helper for alsa

             reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-05  9:11 Christoph Hellwig [this message]
2019-08-05  9:11 ` [PATCH 1/7] dma-mapping: move the dma_get_sgtable API comments from arm to common code Christoph Hellwig
2019-08-05  9:11 ` [PATCH 2/7] dma-mapping: explicitly wire up ->mmap and ->get_sgtable Christoph Hellwig
2019-08-05  9:11 ` [PATCH 3/7] dma-mapping: add a dma_can_mmap helper Christoph Hellwig
2019-08-05  9:11 ` [PATCH 4/7] ALSA: pcm: use dma_can_mmap() to check if a device supports dma_mmap_* Christoph Hellwig
2019-08-05  9:22   ` Takashi Iwai
2019-08-06  5:29     ` Christoph Hellwig
2019-08-06  6:00       ` Takashi Iwai
2019-08-05  9:11 ` [PATCH 5/7] m68knommu: add a pgprot_noncached stub Christoph Hellwig
2019-08-05  9:11 ` [PATCH 6/7] dma-mapping: remove ARCH_NO_COHERENT_DMA_MMAP Christoph Hellwig
2019-08-05  9:11 ` [PATCH 7/7] dma-mapping: provide a better default ->get_required_mask Christoph Hellwig

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