pcm: workaround for avoiding automatic start in mmap mode
In the normal mmap mode, the stream isn't started automatically even after
the data >= start_threshold has been written. However, in the
mmap-emulation mode, the stream is started because it uses
snd_pcm_write_areas() internally.
As a workaround for this inconsistency, start_threshold value is changed
dynamically in sw_parmams and mmap_commit callbacks in mmap-emul plugin.
Meanwhile, start_threshold for slave PCM is set to boundary so that only
this plugin (or the one over it) can control the start of the stream.
This will fix problems in some apps using pulse plugin in the mmap mode.
git://git.alsa-project.org / alsa-lib.git / commit