Re: [PATCH 11/33] dma-mapping: move swiotlb arch helpers to a new header

Robin Murphy
2018-01-10T14:56:01Z

On 10/01/18 08:00, Christoph Hellwig wrote:
> phys_to_dma, dma_to_phys and dma_capable are helpers published by
> architecture code for use of swiotlb and xen-swiotlb only. Drivers are
> not supposed to use these directly, but use the DMA API instead.
>
> Move these to a new asm/dma-direct.h helper, included by a
> linux/dma-direct.h wrapper that provides the default linear mapping
> unless the architecture wants to override it.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
[...]
> drivers/crypto/marvell/cesa.c | 1 +
> drivers/mtd/nand/qcom_nandc.c | 1 +

I took a look at these, and it seems their phys_to_dma() usage is doing
the thing which we subsequently formalised as dma_map_resource(). I've
had a crack at a quick patch to update the CESA driver; qcom_nandc looks
slightly more complex in that the changes probably need to span the BAM
dmaengine driver as well.

In the process, though, I stumbled across gen_pool_dma_alloc() - yuck,
something needs doing there, for sure...

Robin.