On Mon, 05 Nov 2018 16:57:07 +0100, Mike Brady wrote:
One another thing I'd like to point out is that the value given in the patch is nothing but an estimated position, optimistically calculated via the system timer. Mike and I had already discussion in another thread, and another possible option would be to provide the proper timestamp-vs-hwptr pair, instead of updating the timestamp always at the status read.
Agreed — that would give the caller the information needed to do the interpolation for themselves if desired.
And now I wonder whether the problem is still present with the latest code. There was a (kind of) regression in this regard when we introduced the fine-grained hardware timestamping, but it should have been addressed by the commit 20e3f985bb875fea4f86b04eba4b6cc29bfd6b71 ALSA: pcm: update tstamp only if audio_tstamp changed
Could you double-check whether the tstamp field gets still updated even if no hwptr (and delay) is changed?
thanks,
Takashi