Re: [PATCH] ALSA update [6/10] - 2002/07/20

David S. Miller (davem@redhat.com)
Mon, 30 Sep 2002 13:33:01 -0700 (PDT)


From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Date: 30 Sep 2002 13:54:11 +0100

On Mon, 2002-09-30 at 01:53, David S. Miller wrote:
> EISA/ISA DMA is defined as using a hwdev of NULL or requiring
> <16MB address, he is preserving GFP_DMA in those cases.

Firstly the DMA mask on x86 can't be below 24bits, we don't support
allocation from a smaller zone.

Understood.

Secondly what about PCI for 25-31bits -
there we do need to force gfp_dma to have any chance of getting the
right pages

Look at what his code does after the GFP_DMA setting, it goes
a non-GFP_DMA setting, and if the 25-31 bits case is not satisfied
it backs down to GFP_DMA.

Giving the page allocator a mask argument does sound a lot nicer

It's pretty simple to implement too since we do have page_to_phys.
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