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authorTakashi Iwai <tiwai@suse.de>2009-09-04 12:19:36 +0200
committerTakashi Iwai <tiwai@suse.de>2009-09-07 09:01:10 +0200
commita68c4d11336610dc348620766119db09675707c2 (patch)
tree5d12014b8547f6dd13281cd1b6be2bd3d38adfa9 /Documentation/sound
parentb5d10781731ece07bb2049e7743907194a5cc3f1 (diff)
ALSA: dummy - Fake buffer allocations
Instead of allocating the real buffers, use a fake buffer and ignore read/write in the dummy driver so that we can save the resources. For mmap, a single page (unique to the direction, though) is reused to all buffers. When the app requires to read/write the real buffers, pass fake_buffer=0 module option at loading time. This will get back to the old behavior. Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'Documentation/sound')
-rw-r--r--Documentation/sound/alsa/ALSA-Configuration.txt7
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index bb488b575de..ea16e7d184a 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -518,6 +518,7 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
pcm_substreams - Number of PCM substreams assigned to each PCM
(default = 8, up to 16)
hrtimer - Use hrtimer (=1, default) or system timer (=0)
+ fake_buffer - Fake buffer allocations (default = 1)
When multiple PCM devices are created, snd-dummy gives different
behavior to each PCM device:
@@ -526,6 +527,12 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
2 = interleaved without mmap
3 = non-interleaved without mmap
+ As default, snd-dummy drivers doesn't allocate the real buffers
+ but either ignores read/write or mmap a single dummy page to all
+ buffer pages, in order to save the resouces. If your apps need
+ the read/ written buffer data to be consistent, pass fake_buffer=0
+ option.
+
The power-management is supported.
Module snd-echo3g