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From: Christoph Hellwig <hch@lst.de>
To: iommu@lists.linux-foundation.org, Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Robin Murphy <robin.murphy@arm.com>,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: generic DMA bypass flag v3
Date: Tue, 14 Apr 2020 14:25:02 +0200	[thread overview]
Message-ID: <20200414122506.438134-1-hch@lst.de> (raw)

Hi all,

I've recently beeing chatting with Lu about using dma-iommu and
per-device DMA ops in the intel IOMMU driver, and one missing feature
in dma-iommu is a bypass mode where the direct mapping is used even
when an iommu is attached to improve performance.  The powerpc
code already has a similar mode, so I'd like to move it to the core
DMA mapping code.  As part of that I noticed that the current
powerpc code has a little bug in that it used the wrong check in the
dma_sync_* routines to see if the direct mapping code is used.

These two patches just add the generic code and move powerpc over,
the intel IOMMU bits will require a separate discussion.

The x86 AMD Gart code also has a bypass mode, but it is a lot
strange, so I'm not going to touch it for now.

Changes since v2:
 - move the dma mapping helpers out of line
 - check for possible direct mappings using the dma mask

Changes since v1:
 - rebased to the current dma-mapping-for-next tree
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             reply	other threads:[~2020-04-14 12:25 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-14 12:25 Christoph Hellwig [this message]
2020-04-14 12:25 ` [PATCH 1/4] dma-mapping: move the remaining DMA API calls out of line Christoph Hellwig
2020-04-15  2:26   ` Alexey Kardashevskiy
2020-04-15  6:18     ` Christoph Hellwig
2020-04-15 11:21       ` Alexey Kardashevskiy
2020-04-17  7:58         ` Christoph Hellwig
2020-05-05  4:18           ` Alexey Kardashevskiy
2020-05-09  8:19             ` Christoph Hellwig
2020-05-09 14:07               ` Alexey Kardashevskiy
2020-06-03  4:13               ` Alexey Kardashevskiy
2020-07-07  0:43                 ` Alexey Kardashevskiy
2020-07-07 14:51                   ` Christoph Hellwig
2020-04-14 12:25 ` [PATCH 2/4] dma-mapping: inline the fast path dma-direct calls Christoph Hellwig
2020-04-14 12:25 ` [PATCH 3/4] dma-mapping: add a dma_ops_bypass flag to struct device Christoph Hellwig
2020-04-14 12:47   ` Greg Kroah-Hartman
2020-04-18 12:42   ` Joerg Roedel
2020-04-19  8:00     ` Christoph Hellwig
2020-04-19 12:25       ` Joerg Roedel
2020-04-19 14:46         ` Alexey Kardashevskiy
2020-04-14 12:25 ` [PATCH 4/4] powerpc: use the generic dma_ops_bypass mode Christoph Hellwig

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