Re: [PATCH 0/2] Graph fixes for using multiple endpoints per port

From: Kuninori Morimoto
Date: Tue Dec 11 2018 - 19:12:48 EST



Hi Tony, again

> > The issue I have with that it does not then follow the binding doc :)
> >
> > See this part in Documentation/devicetree/bindings/graph.txt:
> >
> > "If a single port is connected to more than one remote device, an
> > 'endpoint' child node must be provided for each link."

My understanding is that 1 "port" is for 1 "physical interface".
In sound case, it is 1 "DAI".
And, 1 "endpoint" is for 1 "connection".

"If a single port is connected to more than one remote device, an
'endpoint' child node must be provided for each link."

This meanns, "If 1 DAI (*1) is connected to multiple remote DAIs(*2),
this connection is indicated by multiple "endpoint"" or something like that.

(*2)
DAIA-endpoint---endpoint--\
DAIB-endpoint---endpoint-----DAI (*1)
DAIC-endpoint---endpoint--/

> > Isn't the I2C TDM case the same as "single port connecected to
> > more than one remote device" rather than multiple ports?

I re-checked https://lkml.org/lkml/2018/3/28/405.
Are MDM6600 / OMAP4 CPU portion, and are CPCAP / WL1285 Codec portion ?
Then, it is not yet supported (on ALSA SoC level?).
If my memory was correct, Lars-Peter had some idea for Mux,
But, not yet implemented I think.

audio-graph[-scu] / simple-card[-scu] are supporting DPCM,
but it is for multiple CPU - single Codec.

Best regards
---
Kuninori Morimoto