On Fri, 2012-08-31 at 10:06 +0800, Raymond Yau wrote:
2012-8-31 上午9:08 於 "Vinod Koul" vinod.koul@linux.intel.com 寫道：
In many modern SoCs the audio DSP can buffer the PCM ring buffer
data, typically
in SRAMs or any other memory available. Today we have no means to represent this buffering and ALSA in some
cases when
device still has to render this buffer but app_ptr is equal to
hw_ptr alsa
wrongly detects an overrun
This patch tries to add a new field "device_buffer" to represent
buffering done in
DSPs. This value is also used for the xrun calculations in ALSA
Signed-off-by: Vinod Koul vinod.koul@linux.intel.com
are these buffer similar to hda 's FIFO ?
No FIFO should only be represented by "delay" not by this one.
can the alsa application use snd_pcm_rewind to rewind the app_ptr ?
Well yes, but if device is deep buffering that it can cause issues. We discussed this and perhaps it would be good to tell device about app pointer and also rewind/fwd, so that it can control this buffering