From a68c4d11336610dc348620766119db09675707c2 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Fri, 4 Sep 2009 12:19:36 +0200 Subject: 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 --- Documentation/sound/alsa/ALSA-Configuration.txt | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation/sound') 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 -- cgit v1.2.3