On Thu, Jun 02, 2016 at 10:40:58AM -0700, Caleb Crome wrote:
> On Thu, Jun 2, 2016 at 10:17 AM, Mark Brown <broonie@kernel.org> wrote:

> > Well, if you specifically mean TDM as opposed to multi-channel our
> > general support for that isn't good (mainly due to lack of demand).  It
> > sounds like you're more interested in multi channel here though.

> I must be missing something.  To me, TDM is synonymous with
> multi-channel on a single wire. The datasheets of codecs and SoCs

TDM, at least in the sense Linux is using it, is multiple *unrelated*
audio streams on a single wire.  Any multi-channel audio stream is TDM
in some sense but the trivial extension to add two or more channels
isn't really a big deal.  This is for things more complex than just
stuffing more bytes of data onto a wire where there are going to be some
timeslots that the device should ignore as they're going to/from other
devices (or at least other streams even if the same chip is handling
them).

> (I recall there is also a specific TDM format with something like 384
> slots per frame, which is a well defined thing, but that's not what
> I'm talking about.  That's used just for telephony I beleive).

You're thinking of H.1x0 CTBus which is genuine TDM, used for routing
single channel audio streams between multiple PCI (H.100) or cPCI
(H.110) cards in a system.  It does way more than 384 slots, 4096
8kHz 8 bit timeslots IIRC.

> What's the linuxy name for what the datasheets call TDM format with
> slots > 2?  Do we just call that 'multi-channel', or specifically say,
> 'channels_max > 2'?  I was always under the assumption that's what TDM
> meant.

We don't particularly call it anything, it's such a trivial extension.