On Tue, Feb 22, 2022 at 09:06:48AM +0000, David Laight wrote:

From: Christoph Hellwig

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Sent: 22 February 2022 08:47

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Hmm.. for this specific case, What about allocating two buffers
for DMA_TO_DEVICE and DMA_FROM_DEVICE at initialization time?

That will work, but I don't see the benefit as you'd still need to call
dma_sync_single* before and after each data transfer.

For systems with an iommu that should save all the iommu setup
for every transfer.

So does allocating a single buffer as in the patch we are replying to.