Re: dmaengine skip unmap (was: Re: [PATCH v4 5/6] dmaengine: Driverfor the Synopsys DesignWare DMA controller)

From: Haavard Skinnemoen
Date: Fri Jul 04 2008 - 10:48:22 EST


Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> The one thing that stands out is that this driver does not unmap the
> source or destination buffers (and I now notice that fsldma is not doing
> this either, hmm...). Yes, it is a no-op on avr32, for now, but the
> dma-mapping-api assumes that dma_map is always paired with dma_unmap. I
> remember we discussed this earlier and that discussion inspired the
> patch below. The end result is that dw_dmac can try to automatically
> dma_unmap the buffers unless an intelligent client, like the mmc driver,
> has disabled unmap.
>
> Thoughts?

Looks reasonable. I'll update the dw_dmac driver and post a new version
in a few moments.

Haavard
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