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. > The best way I have found to reproduce the bug is to use dmix in > combination with Chromium, which opens the audio device multiple > times in threads. Anecdotally, the problems appear to have increased > with faster CPUs. > > Since applying this patch I have not had problems, where previously > they would occur several times a day. > > This patch addresses the following issues: > > * 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. > * Remove chip->last_period: > > It's trivial to derive from pipe->last_counter, and inside pipe > is where it more logically belongs. This has less scope for bugs > as it is not wrapped to the buffer length. Ok. > * Remove the accessing of pipe->dma_counter twice in the interrupt > handler: Why twice? > +static int snd_echo_poll_substream(struct snd_pcm_substream *substream) > [...] > static irqreturn_t snd_echo_interrupt(int irq, void *dev_id) > [...] Looks fine to me. -- Giuliano.
