From: Giuliano Pochini <pochini@shiny.it>
To: Tehn Yit Chin <tehn.yit.chin@gmail.com>
Cc: alsa-devel@lists.sourceforge.net
Subject: RE: how does alsa keep passing data into driver?
Date: Fri, 14 Oct 2005 09:36:33 +0200 (CEST) [thread overview]
Message-ID: <XFMail.20051014093633.pochini@shiny.it> (raw)
In-Reply-To: <bf04f99c0510131947m1a5e0a68n631b761818887222@mail.gmail.com>
On 14-Oct-2005 Tehn Yit Chin wrote:
> I am trying to understand how the ALSA pass PCM data to the driver. I have
> understand that when the driver starts up, a start trigger event is created
> and some PCM data is passed in. After that, how does the subsequent PCM data
> get pass into the driver?
The ALSA middle layer passes PCM data to the driver only if the driver
attaches a function to the .copy() callback. Otherwise (and this is the
most common case) the ALSA ml copies data to/from the buffer on its own.
> I also realise that a pointer event is generated, but from the docs, the
> pointer event is for figuring out the current position.
Yep. ALSA needs to know what part of the buffer has been consumed so it
can copy new data to/from that part.
--
Giuliano.
-------------------------------------------------------
This SF.Net email is sponsored by:
Power Architecture Resource Center: Free content, downloads, discussions,
and more. http://solutions.newsforge.com/ibmarch.tmpl
next prev parent reply other threads:[~2005-10-14 7:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-14 2:47 how does alsa keep passing data into driver? Tehn Yit Chin
2005-10-14 7:36 ` Giuliano Pochini [this message]
2005-10-16 14:00 ` Tehn Yit Chin
2005-10-16 15:26 ` James Courtier-Dutton
2005-10-16 19:37 ` Eliot Blennerhassett
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=XFMail.20051014093633.pochini@shiny.it \
--to=pochini@shiny.it \
--cc=alsa-devel@lists.sourceforge.net \
--cc=tehn.yit.chin@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.