Re: [RFC PATCH 1/2] soundwire: add support for static port mapping

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On 1/21/21 9:41 AM, Srinivas Kandagatla wrote:


On 21/01/2021 14:56, Pierre-Louis Bossart wrote:


Port allocations are something like this:

RX: (Simple)
Port 1 -> HPH L/R
Port 2 -> CLASS H Amp
Port 3 -> COMP
Port 4 -> DSD.

TX: (This get bit more complicated)
Port 1: PCM
Port 2: ADC 1 & 2
Port 3: ADC 3 & 4
Port 4: DMIC-0, DMIC-1, DIMC-2 , DMIC-3 and MBHC
Port 5: DMIC-4, DMIC-5, DMIC-6 and DMIC-7

We handle the port allocation dynamically based on mixer and dapm widgets in my code! Also channel allocations are different for each function!

Sorry, I am not following here. What is dynamic here and use-case dependent? And is this a mapping on the master or the codec sides that you want to modify?

[SLAVE]-------[MASTER]
NA-------------Port 1: PCM
Port 1---------Port 2: ADC 1 & 2
Port 2---------Port 3: ADC 3 & 4
Port 3---------Port 4: DMIC-0, DMIC-1, DIMC-2 , DMIC-3 and MBHC
Port 4---------Port 5: DMIC-4, DMIC-5, DMIC-6 and DMIC-7


Mapping is still static however Number of ports selection and channel mask will be dynamic here.


Example: for Headset MIC usecase we will be using Slv Port1, Slv Port3 along with Mstr Port2 and Master Port4

Similarly for usecases like Digital MIC or other Analog MICs.

Sorry, I must be thick here, but in my experience the choice of Digital or analog mics is a hardware design level not a use-case one. Using ADC 1 & 2 at the same time as DMICs is very surprising to me. You'd have different sensitivities/performance, not sure how you would combine the results.

I also don't see how a headset mic can both use Analog and digital, unless we have a different definition of what a 'headset' is.

Does this help and can you align on what Intel started with?

Firstly, This is where the issue comes, if we go with the suggested(dai->id) solution, we would end up with a long list of dai-links with different combinations of both inputs/output connections and usecases. Again we have to deal with limited DSP resources too!

Secondly, The check [1] in stream.c will not allow more than one master port config to be added to master runtime. Ex: RX Port 1, 2, 3 is used for Headset Playback.

I am confused here, we do have examples in existing codec drivers where we use multiple ports for a single stream, e.g. for IV feedback we use 2 ports.

Is this on multi_link? which is why it might be working for you.

no, this is done at the codec driver level, which has no notion of multi-link. we pass a port_config as a array of 2.

Currently we have below check in sdw_stream_add_master().

if (!bus->multi_link && stream->m_rt_count > 0) {
     dev_err(bus->dev, "Multilink not supported, link %d\n", bus->link_id);
     ret = -EINVAL;
     goto unlock;
}

If we have single master(like my case) and dai-links which have more then one port  will be calling  sdw_stream_add_master() for each port, so m_rt_count above check will fail for the second call!

if you use multiple ports in a given master for the same stream, you should have the m_rt_count == 1. That's a feature, not a bug.

A port is not a stream... You cannot call sdw_stream_add_master() for each port, that's not what the concept was. You allocate ONE master_rt per master, and that master_rt deals with one or more ports - your choice.

A 'stream' is an abstract data transport which can be split across multiple masters/sales and for each master/slave use multiple ports. When calling sdw_stream_add_master/slave, you need to provide a port_config/num_ports to state which ports will be used on that master/slave when using the stream. That's how we e.g. deal with 4ch streams that are handled by two ports on each side.

To up-level a bit, the notion of 'stream' is actually very very similar to the notion of dailink. And in fact, the 'stream' is actually created for Intel in the dailink .startup callback, so I am quite in the dark on what you are trying to accomplish.



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