Re: Scatter Gather DMA

[Takashi Iwai <tiwai@suse.de>]

At Wed,  5 Mar 2003 12:09:21 -0400,
mjander wrote:
> 
> Hi,
> 
> Another question... :)
> 
> The Aureal Vortex has Scatter Gather DMA's for each audio channel.
> But these SG DMA
> support only max 4 pages. Each page can have a programable size of
> upto 4 KB.
> I was studying the ALSA SG scheme and it doesnt seme to fit into
> the aureal vortex
> SG buffer scheme, because ALSA, as far as i understood, only
> allows pages of the kernel PAGE_SIZE size, and allocates as many
> pages (without cound limit ?) until the buffer size is  reached.

then you can define max_buffer_bytes as 4 * 4096.
then sg-allocator will allocate up to 4 pages.

> But the PAGE_SIZE around 0x400 or 0x800, which is rather small.

sorry, what are these numbers?

> On the Aureal vortex soundcard side i have 4 registers for page
> base address, and some sort  of config regs to configure each page
> size and the next page for each page. I just dont understand how
> could i plug this two apparently incompatible things together.


Takashi


-------------------------------------------------------
This SF.net email is sponsored by: Etnus, makers of TotalView, The debugger 
for complex code. Debugging C/C++ programs can leave you feeling lost and 
disoriented. TotalView can help you find your way. Available on major UNIX 
and Linux platforms. Try it free. www.etnus.com