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

On Mon, Mar 10, 2008 at 6:23 AM, Paul Davis <paul@email-addr-hidden> wrote:
>
> 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.

Yes, that's what I was thinking about. Clearly the PCI Device/Vendor
IDs are not sufficient to handle this.
>
>
> > 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.
>

And let's not drop out 1394 or other external buses. The issue isn't
USB as much as it's an external network of devices that can both be
rewired easily and in some cases come and go in strange ways. If
you're using an external USB powered hub, for instance, and the power
isn't applied for some period of time the system thinks the device is
gone when it's just that someone kicked out the wall wart. Making that
sort of support of external devices really robust would take some
serious thinking.

Anyway, I appreciate your inputs and will likely file an enhancement
request just to put the idea out there. I suspect a first step could
be udev in some hand crafted way. I may explore that idea also.

Cheers,
Mark
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Received on Mon Mar 10 16:15:04 2008