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From: Christoph Hellwig <hch@lst.de>
To: "Horia Geantă" <horia.geanta@nxp.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Christoph Hellwig <hch@lst.de>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	linux-imx@nxp.com
Subject: Re: [PATCH] swiotlb: sync buffer when mapping FROM_DEVICE
Date: Wed, 22 May 2019 14:32:43 +0200	[thread overview]
Message-ID: <20190522123243.GA26390@lst.de> (raw)
In-Reply-To: <20190522072018.10660-1-horia.geanta@nxp.com>

I'm a little worried about this.  While it looks functionally correct
we have surived without it, and doing another copy for every swiotlb
dma mapping from the device looks extremely painful for the typical use
cases where we expect the device to transfer the whole mapping.

I'd be tempted to instead properl document the current behavior and
introduce a new DMA_ATTR_PARTIAL flag to allow for partial mappings.

  reply	other threads:[~2019-05-22 12:33 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22  7:20 [PATCH] swiotlb: sync buffer when mapping FROM_DEVICE Horia Geantă
2019-05-22 12:32 ` Christoph Hellwig [this message]
2019-05-22 12:50   ` Robin Murphy
2019-05-22 13:09     ` Christoph Hellwig
2019-05-22 13:25       ` Robin Murphy
2019-05-22 13:34         ` Christoph Hellwig
2019-05-22 13:55           ` Robin Murphy
2019-05-23  5:35             ` Marek Szyprowski
2019-05-23 16:25               ` Horia Geanta
2019-05-23 16:43               ` Christoph Hellwig
2019-05-23 17:53                 ` Horia Geanta
2019-05-23 18:05                 ` Robin Murphy

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