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

[Russell King <rmk+alsa@arm.linux.org.uk>]

On Mon, Mar 01, 2004 at 04:41:00PM +0100, Takashi Iwai wrote:
> 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 think you've assumed that:

+       res = dma_alloc_coherent(dev, PAGE_SIZE << pg, dma, GFP_KERNEL);

in snd_malloc_dev_pages() uses GFP_ATOMIC.  Please look closer.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core


-------------------------------------------------------
SF.Net is sponsored by: Speed Start Your Linux Apps Now.
Build and deploy apps & Web services for Linux with
a free DVD software kit from IBM. Click Now!
http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click