Messages in this thread | | | Subject | Re: [RFC PATCH 1/2] soundwire: add support for static port mapping | From | Srinivas Kandagatla <> | Date | Thu, 21 Jan 2021 11:35:20 +0000 |
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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/drivers/soundwire/stream.c?h=v5.11-rc4#n1294 >
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