On Mon, 6 Jan 2003, Fred Gleason wrote:
> On Sunday 05 January 2003 10:05, Jaroslav Kysela wrote:
>
> > Well, you're talking about PCM devices (subdevices are one level after
> > devices):
> >
> > cards -> pcm devices -> pcm subdevices
>
> What are the differences between a "device" and a "subdevice" in general? Is
> this indicative of some underlying hardware architecture, or is it a purely
> logical/virtual artifact?
We use subdevices mainly for hardware which can mix several streams
together. It's quite impractical to have 32 devices with exactly same
capabilities. The subdevices can be opened without a specific address, so
the first free subdevice is opened. Also, we temporary use subdevices for
hardware with alot of streams (I/O connectors) - for example MIDI. There
are several limits given by used minor numbers (8 PCM devices per card, 8
MIDI devices per card etc.).
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
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