From mboxrd@z Thu Jan  1 00:00:00 1970
From: James Courtier-Dutton <James@superbug.demon.co.uk>
Subject: Sound card DMA questions.
Date: Tue, 20 Jul 2004 02:18:12 +0100
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With DMA accesses, one has a sound card connected to a PCI bus, which is 
then connected to the RAM.

The sound card will schedule a DMA transfer.

My questions are:
1) What size is the DMA transfer?
2) Are the min/max limits on how many bytes can be passed on a transfer?
3) When does the transfer happen. At period boundarys or when ?
4) What triggers a user land poll() to return. An irq based 
snd_period_elapsed() call, or something else?

And finally,
5) if I am reverse engineering a card, how can I discover these min/max 
values?

James


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