[alsa-devel] [PATCH - AAF PCM plugin 0/7] Introduce AVTP Audio Format (AAF) plugin

[Guedes, Andre]

Hi Pierre,

On Mon, 2018-10-22 at 11:51 -0500, Pierre-Louis Bossart wrote:
> > > The codes look mostly good.  I'll post just a new nitpicking
> > > later.
> > > 
> > > But I'd like to postpone the merge until Pierre back from his
> > > vacation and getting some feedback from him.
> 
> I'm back and will look at those patches this week.

Thanks for letting me know. I just found a bug when multiple streams
are running at the same time. I have it fixed already, and since
Takashi's comments have been addressed as well, I'm going to push the
v2 so you can review the latest code.

I'm finishing testing the v2 series and should post it by tomorrow.

> I'll probably have to talk to Andre to figure out how the clocks are
> managed, I didn't fully understand the answers from August that 
> "The plugin requires both CLOCK_REALTIME and PTP to be synchronized,
> and this can add some usage scenarios limitation, indeed. However,
> the scenario you described looks still feasible. For instance, at the
> host running as PTP master, we could have NTP disciplining
> CLOCK_REALTIME (ntp daemon) and CLOCK_REALTIME disciplining PTP
> (phc2sys daemon). At the hosts running as PTP slave, we have PTP
> disciplining CLOCK_REALTIME (phc2sys daemon). This way,
> CLOCK_REALTIME time from all systems is NTP time while CLOCK_REALTIME
> and PTP clock are in sync"
> For audio usages we typically have all clocks derived from ART, and
> we'd need the CLOCK_MONOTONIC_RAW to align with the PTP clock to
> allow for loopbacks without ASRC (or ASRC between the audio clock and
> ART). Not sure who uses CLOCK_REALTIME for audio?

Sure, let's follow up on this when you're available.

> > > BTW, what's the good way to test this stuff locally?
> > 
> > The minimal setup to test the plugin requires 2 machines connected
> > back-to-back. The machines should be equipped with a TSN-capable
> > NIC that supports PTP and FQTSS features. I'm using Intel i210 NIC.
> > 
> > doc/aaf.txt provides detailed instructions on how to setup the PTP
> > and FQTSS features from the NIC as well as how to run the plugin.
> > If you have any trouble with the instructions, please let me know
> > and I'll fix it for the next series version.
> 
> I was planning to experiment with two stacked MinnowBoard Turbot quad
> core dual ethernet [1], they have i210 support and would be the
> cheapest/compact way to test all this. You can connect to each board
> from your workstation with one of the two ports for
> updates/command/control and dedicate the second port to AVB/TSN
> transfers between the two boards.

I'm not using MinnowBoard Turbot but the setup you described here is
pretty much what my testing setup is.

Regards,

Andre
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