Re: [PATCH -mm 1/4] DMA-API.txt: add dma_sync_single/sg API description

[David Miller <davem@davemloft.net>]

From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date: Thu,  4 Feb 2010 12:13:22 +0900

> This adds the description of the following eight function:
> 
> dma_sync_single_for_cpu
> pci_dma_sync_single_for_cpuvoid
                             ^^^^

That "void" is probably some cut and paste error :-)

> dma_sync_single_for_device
> pci_dma_sync_single_for_device
> dma_sync_sg_for_cpu
> pci_dma_sync_sg_for_cpu
> dma_sync_sg_for_device
> pci_dma_sync_sg_for_device
> 
> It was unclear that the API permits a partial sync (some network
> drivers already do though). I made it clear that the sync_single API
> can do a partial sync but the sync_sg API can't.
> 
> We could do a partial sync with the sync_sg too, however, it's
> difficult for driver writers to correctly use the sync_sg API for a
> partial sync since the scatterlists passed in to the mapping API can
> be modified. It's unlikely that driver writers want to do a partial
> sync with the sync_sg API (because the sync_sg API are usually used
> for block drivers). So I think that it's better to forbid a partial
> sync with the sync_sg API.
> 
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

Acked-by: David S. Miller <davem@davemloft.net>