[pulseaudio-discuss] Order-based or priority-based default device?

[Arun Raghavan]

On Wed, 2011-09-07 at 15:37 +0200, David Henningsson wrote:
[...]
> I've tried to talk to a few people, and from what I can tell, there is 
> no point in time when the system can be considered to be fully "up and 
> running". This means e g, if a new bluetooth device shows up say 30 
> seconds after PulseAudio starts, we don't know if this was because 
> someone actually connected the bluetooth headset at that point, or if it 
> was connected from start but took 30 seconds to respond and negotiate 
> with the bluez stack. Same goes for USB, and in theory other devices as 
> well, but I've never seen it happen in practice to anything internal/PCI.
> 
> Also, this applies not only at boot, but also at resume from suspend or 
> hibernate.
> 
> Given that lack of information from the kernel/hardware, I can only 
> assume that order-based handling is bound to fail. And so is 
> module-switch-on-connect, that implements this. (And so is Ubuntu's 
> suspend/resume script, btw.)
> 
> This leaves us rule/priority-based policy d ecisions, which I believe is 
> what Colin thinks as well. Comments?

IMO, this approach to device plugging is a bit of a cop-out. Maybe a
device appearing 10 seconds after boot/resume is not hot-plugged, but a
device that appears >2 minutes almost certainly is. So I think with
heuristics, we can deal with this. For example, we call the system
booted when there are no new events for X seconds (the value of X can be
the subject of much bikeshedding), we call the system booted/resumed.

I'm not involved in the bits of the stack that do this, so feel free to
point out if I'm missing something.

-- Arun