On Tue, 16 Jun 2020, Giuliano Pochini wrote: > On Tue, 16 Jun 2020 14:17:43 +0100 > Mark Hills <mark@xxxxxxxx> wrote: > > > Distorted audio appears occasionally, affecting either playback > > or capture and requiring the affected substream to be closed by > > all applications and re-opened. > > Yes, it also happens here very rarely (one time every some months) and I > failed to reproduce the problem. It frustrated me for years, but I had other work I needed to do. Eventually I was working around it several times a day :-/ [...] > > * Check for progress using the counter from the hardware, not after > > it has been truncated to the buffer. > > > > There appears to be a possible bug if a whole ringbuffer advances > > between interrupts, it goes unnoticed. > > In that case the stream must be restarted anyway due to xrun. Yes, but I think it will go unnoticed, so you don't know to re-start. [...] > > * Remove the accessing of pipe->dma_counter twice in the interrupt > > handler: > > Why twice? Yes, the interrupt handler calls pcm_pointer() directly to make a decision. Then it calls snd_pcm_period_elapsed(), which itself goes on to make another call to pcm_pointer(), by this time the bus mastering of the interface has adjusted the counter. The new code processes the counter only once, and this is easier to rationalise whether there are bugs. -- Mark
