Takashi Iwai wrote:
The sync ioctl is to block the operation until all samples are played. But, it's a bit strange that the stream stops after this. It should be an underrun instead (and OSS recovers by itself).
I figured it out. When the application starts, my driver gets a call to the _hw_params and _prepare functions. When the app calls SNDCTL_DSP_SYNC, those two functions get called again. At that point, the DMA controller gets re-programmed. For some reason, it doesn't like that. The DMA never actually starts.
I moved some of the DMA programming code to my _open function (where it belongs, anyway), and now bplay works.
Well, almost. After about a second into playback, it skips a little bit. And then about 4-5 seconds later, bplay calls SNDCTL_DSP_SYNC, and that causes playback to pause for about a second.
I need to figure out why bplay is calling sync, and why the audio skips in the beginning.