linux-kernel - Re: [PATCH -mm 1/4] DMA-API.txt: add dma_sync

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Message-Id: <20100204123056Q.fujita.tomonori@lab.ntt.co.jp>
Date:	Thu, 4 Feb 2010 12:31:23 +0900
From:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
To:	davem@...emloft.net
Cc:	fujita.tomonori@....ntt.co.jp, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, James.Bottomley@...e.de
Subject: Re: [PATCH -mm 1/4] DMA-API.txt: add dma_sync_single/sg API
 description

On Wed, 03 Feb 2010 19:21:23 -0800 (PST)
David Miller <davem@...emloft.net> wrote:

> From: FUJITA Tomonori <fujita.tomonori@....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 :-)

Oops.


> > 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@....ntt.co.jp>
> 
> Acked-by: David S. Miller <davem@...emloft.net>

Thanks,

I found other two typos in the commit log so here's the update.

=
From: FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>
Subject: [PATCH -mm 1/4] DMA-API.txt: add dma_sync_single/sg API description

This adds the description of the following eight function:

dma_sync_single_for_cpu
pci_dma_sync_single_for_cpu
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 API 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't
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@....ntt.co.jp>
Acked-by: David S. Miller <davem@...emloft.net>
Cc: James Bottomley <James.Bottomley@...e.de>
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