[alsa-devel] hw_params function and OSS emulation
tiwai at suse.de
Wed Aug 22 17:39:03 CEST 2007
At Wed, 22 Aug 2007 10:02:11 -0500,
Timur Tabi wrote:
> Takashi Iwai wrote:
> > Alternatively, you can remember the last allocated buffer-size and
> > re-use the same buffer if the requested size is less than it.
> > Since the buffer size change won't happen _so often_ (even via OSS
> > emulation), this would work well in practice, too.
> Hmm... Neither of these options is really that great.
... but no other way :) The buffer size is dynamically configurable,
per design. That's all.
> I think I like the idea
> of pre-allocating the buffer in .new. What is a reasonable maximum size for
> the DMA buffer? 32KB seems small to me.
AFAIK, 64kB seems sufficient in most cases.
> When I was testing OSS emulation,
> the first call to .hw_params passed a DMA buffer size of over 1MB!
The driver should deny a too large size if it's unrealistic.
But 1MB is realistic for many systems. So, the number depends on the
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