12.04.2013 20:55, Lars-Peter Clausen пишет:
On 04/12/2013 06:37 PM, Stas Sergeev wrote:
Thanks for an explanation! But what happens when the DAI is considered mute by the effect of such intersection? From what I can see, no callbacks from the DAI driver are called in this case (this is expected), but no error is returned to userspace, and, more importantly, the playback speed is still correct, so the userspace can get a playback position as if the playback is fine. While during the normal playback, if I stop calling snd_pcm_period_elapsed(), userspace is no longer getting the right position. That's why I am confused, I can't easily explain this "no sound but otherwise fine playback" effect, so I am a bit reluctant to try explaining this in a commit msg. Are there are some fallbacks? Such as when the DAI is considered mute, it gets somehow emulated, with the use of the system clock for correct timing etc?
That's actually a bit strange indeed, since you should get an error when you try to open the pcm device.
Ah great! Next week I'll double-check that the fall-back is actually in userspace (in an android media stack perhaps), and that will be enough info for the reasonable commit msg. :) Thanks for your help!