[Sound-open-firmware] about SOF 1.2 topology support

[Keyon Jie]

Hi all,

I am collecting the 1.2 topology support gap and try to figure out the 
priority and workload about that, and what I can imagine now are:

1. Multiple BEs(SSPs) support;
     This may need add BE definition for SOF from tplg file.

2. Reference tplg m4 for different platforms, including 
byt/cht/bdw/hsw/apl/cnl.
     This may need enable/verify types of pipeline(e.g. src, media, 
low-latency) can works separately and stably.

3. Refine host component buffer size, from pipeline format to pcm 
capability max, and use buffer_set_size in params() for each 
playback/capture.
     This means we can support different input formats(in the capability 
list) with a single tplg file.

4. Dynamic/hostless pipeline support.
     We have requirement to switching PCM(FEs) to different BEs at 
runtime, and also host-less(e.g. tone may already support. 
SSP2->SRC->SSP4, ...). we can add kcontrols to control those host-less 
pipeline.
5. Add a kcontrol for each SSP BE to switch loopback on/off, for test 
purpose.
...

I will work on #5, then #1, then #2. I think Yan is working on something 
related with #3, and #4 may have dependency to #1.

Any comment about these are welcomed.

Thanks,
~Keyon