[LAU] Many identical cards - how to keep them straight

Paul Davis paul at linuxaudiosystems.com
Mon Mar 10 09:23:43 EDT 2008


On Mon, 2008-03-10 at 06:17 -0700, Mark Knecht wrote:

> For example if I have 3 HDSP9652's in a system in a system I could in
> theory have the ADAT cables from two of the cards going to a mixing
> desk, the lower half of the desk being card 0 and the upper half being
> card 1. (Or two desks in parallel.) The 3rd card might be talking to
> an external rack of signal processors. What is important is that the
> system not arbitrarily change the 3 groups of connections the next
> time I boot the system or I find myself mixing inside of a reverb unit
> and wondering why my mixer sounds dry.
> 
> In Windows the system seems to read the card's firmware where it finds
> some unique ID value, possibly just the PCI device and vendor IDs, 

its certainly not just that, since this doesn't uniquely identify the
cards.every RME HDSP card has the same device+vendor info. a quick check
with lspci -vvv doesn't reveal a serial ID. its possible that since in
most (all?) systems, the PCI slot always has a unique IRQ w.r.t. other
PCI slots, that a combination of the PCI product ID and the IRQ might
work, but I am not sure.

> While it may not be much of a problem for most of us folks would there
> be any reason not to file an enhancement request with the Alsa devs on
> this issue?

I can't think of one. Keep in mind that what there are really two
different scenarios:

  a) PCI devices: the device discovery order is dependent on
       the PCI bus controller (probably)
  b) USB devices: device discovery order is dependent on the
       USB bus controller, the devices and maybe even the user.
  
--p




> Thanks,
> Mark




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