Re: [PATCH] 1/3 Implement generic device DMA mapping support

[Takashi Iwai <tiwai@suse.de>]

Hi,

At Sun, 29 Feb 2004 22:38:20 +0000,
Russell King wrote:
> 
> This is the first shot at this - I've tested it on ARM, covering both
> ISA ALSA devices on a PCI machine, and driver model devices on a non-
> PCI, non-ISA machine.  However, it needs more testing.  Can people
> on alsa-devel please test these patches.
> 
> This patch adds support for the generic device/driver model to ALSA
> for the sole purpose of supporting their DMA mapping functionality.
> 
> This patch changes snd_malloc_sgbuf_pages() to use this dma mapping
> functionality.

thanks for the patch.  using struct device is nice for
generalization.

after a short glance, the only drawback i found is that you disabled
the single pci page allocation hack for i386.  this was needed to
cover the non-atomic page allocation.
for example, sb live needs to allocate more than 100MB single pages
for the wavetable data.  the allocation with GFP_ATOMIC can fail
easily in such a case, althogh there is enough memory after swapping.
maybe we can leave this function as another...


i also think that we can split pre-allocate stuffs and initialization
stuffs to simplify.  that is, we provide the initializer
	snd_pcm_lib_set_dma_type(pcm, SND_DMA_PCI, ...);
or somethine like that.  and call a single function,
snd_pcm_lib_preallocate_buffers_for_all().
having preallocate_*() stuffs for each DMA type is not necessary.


Takashi


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