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| author |   Takashi Iwai <tiwai@suse.de> | 2009-09-04 12:19:36 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2009-09-07 09:01:10 +0200 |
| commit | a68c4d11336610dc348620766119db09675707c2 (patch) | |
| tree | 5d12014b8547f6dd13281cd1b6be2bd3d38adfa9 /Documentation | |
| parent | ALSA: dummy - Fix the timer calculation in systimer mode (diff) | |
| download | linux-dev-a68c4d11336610dc348620766119db09675707c2.tar.xz linux-dev-a68c4d11336610dc348620766119db09675707c2.zip | |
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')
| -rw-r--r-- | Documentation/sound/alsa/ALSA-Configuration.txt | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt index bb488b575def..ea16e7d184a4 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 |