[PATCH] arm/dma-mapping: Clarify arm_*_sync_sg_* usage

[Daniel Kurtz]

Hi Robin,

On Wed, Sep 23, 2015 at 3:06 AM, Robin Murphy <robin.murphy at arm.com> wrote:
> The comments on the arm_iommu_sync_sg_* functions are misleading, and
> do not hold up to scrutiny against the DMA API documentation. Since
> cache maintenance is performed on the CPU addresses of the original
> list, not the virtual DMA entries filled in by arm_iommu_map_sg,
> passing in fewer than the original number of entries can only result
> in the corresponding subset of the buffer being flushed/invalidated
> while the rest is skipped, which is almost certainly not what the
> caller desires.
>
> Fix all the relevant comments to say the correct thing; no functional
> difference for arm_dma_sync_sg*, as the current implementation of
> arm_dma_map_sg always returns the same number of entries as passed in
> if it succeeds.
>
> Signed-off-by: Robin Murphy <robin.murphy at arm.com>

Thanks for fixing these confuse comments!

Reviewed-by: Daniel Kurtz <djkurtz at chromium.org>