On 07/03/2014 06:15 PM, Vinod Koul wrote:
On Thu, Jul 03, 2014 at 01:18:46PM +0100, Mark Brown wrote:
BUT Now thinking over this again, does this make sense do do with multiple codecs??
For folks haveing decoders in DSP inside SoC, the compressed device will be actually a FE. The BE will be PCM to which codec would be linked. The folks supporting decoders inside codec like WM wont ever need this.
Mark, do you agree to this?
So re-thinking again on why we need this??
The use case tends to be for applications that have one device per physical output. This isn't normally mobile, it's normally high performance audio applications where people are doing things to try to electrically isolate the analogue outputs or dealing with high power so need to keep speaker outputs physically separate. I can imagine set top box type applications (which do use offloaded media decode) doing this.
Not sure if I follow you, I have no idea of how these systems work.
But if sound card has compressed device it would need to represent using DPCM as we don't know the decoder PCM output. The multiple codecs would then connect to the PCM BE. So on Compressed FE, we wont have multiple codecs.
For codecs, the compressed audio will go to one codec, multiple ones wont make sense.
So how can we have a situation where we have compressed device linked to multiple codecs?
If the assumption is that a DAI link that has a compressed DAI on the CPU side is never connected to a 'real' CODEC (or multiple CODECS) on the CODEC side. I think we can just leave soc-compress.c alone and just add a sanity check to make sure that num_codecs is always 1.
- Lars