Thanks Pierre for your inputs,
On 20/01/2021 22:15, Pierre-Louis Bossart wrote:
On 1/20/21 12:01 PM, Srinivas Kandagatla wrote:
Some of the soundwire controllers can have static functions assigned to each port, like some ports can only do PCM or PDM. This is the situation with some of the Qualcomm Controllers.
In such cases its not correct to assign/map any free port on master during streaming.
So, this patch provides a way to pass mapped port number along with the port config, so that master can assign correct ports based on the provided static mapping.
I am not sure I understand the problem or what's different between Intel and Qualcomm.
On the Intel side we also have fixed-function ports, some for PDM and some for PCM. They are not interchangeable, and they are also dedicated for each link.
That is good to know!
We don't dynamically allocate ports on the master side, the mapping is defined by the dai->id and is static. There is a 1:1 relationship between dai->id and port_number. See intel_register_dai() and intel_hw_params() in drivers/soundwire/intel.c
In the machine driver we make use of specific master DAIs in the dailink definitions, just like regular ASoC solutions, so which DAIs you use in the machine driver defines what ports end-up being used. There is nothing fancy or dynamic here, the dai/port allocation is defined by the dailinks. This is a static/worst-case allocation, we don't reassign ports depending on use-cases, etc.
The only thing that is dynamic is that the programming of each port is handled based on the bandwidth needs of that port, i.e if you play 16 or 24 bits you'd get fewer or more bitSlots allocated to that dai/port, and the DPn registers are updated if you have concurrent streaming on other ports. If you only have a fixed set of payloads, as in the existing amplifier cases, you can hard-code this allocation as well.
Yes, it will work for the existing WSA881x amplifier case.
Am preparing patches for a new QCOM codec driver WCD938x (TX and RX) connected via Soundwire,
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!
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.
But if we have a static mapping table of the ports then this will provide more flexibility to codec driver! And we can dynamically select ports based on the usecase or active dapm path!
--srini
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/driv...