From: James Courtier-Dutton <James@superbug.demon.co.uk>
To: alsa-devel@lists.sourceforge.net
Subject: Sound card DMA questions.
Date: Tue, 20 Jul 2004 02:18:12 +0100 [thread overview]
Message-ID: <40FC72D4.1040900@superbug.demon.co.uk> (raw)
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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next reply other threads:[~2004-07-20 1:18 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-20 1:18 James Courtier-Dutton [this message]
2004-07-20 7:39 ` Sound card DMA questions Giuliano Pochini
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