Re: [PATCH v2 0/7] ASoC: Intel: avs: Soundwire support

[Pierre-Louis Bossart]

On 11/4/26 10:14, Cezary Rojewski wrote:
> On 11/3/2026 6:20 PM, Pierre-Louis Bossart wrote:
>>
>>> Also, the existing code fetches the PDIs based on pre-defined "dai_id".
>>> That's not the case for the avs-driver.  It simply asks: "is any PDI
>>> free?" and assigns it for the substream if one is found.
>>> No predefining.  Again, this aligns with how HDAudio streaming is done.
>> Yeah but at the end of the day there's a 1:1 mapping between cpu_dai and
>> PDI, no?
>>
>> All PDIs are created equal, a dynamic mapping doesn't make things more
>> efficient. It just makes things more complex to debug since you don't
>> have a fixed mapping between dailinks/stream/cpu_dai/PDI.
>>
>> Put differently, couldn't the AVS driver work around that fixed mapping
>> to avoid changes to legacy platforms that have shipped many moons ago?
> 
> Kind disagree on the debugging part.  Having SDW streaming follow
> closely to what is done for HDAudio from the beginning (no hardcodes)
> makes it easier for a developer to debug stuff.  OTOH if one of these
> two follows a completely different path, the developer has to have such
> hardcodes in mind when debugging the PCM code or even when looking at
> the topology.
> 
> At the same time, I'm not going anywhere and I do intend to work with
> Peter and Kai to update the common code. Simply put, such a refactor
> would be routed through SOF GH first.
The machine driver selects the first available cpu_dai when creating a
dailink. It doesn't really add much value to add a second level of
freedom to select PDIs, since in practice it'll select the first as
well. PDIs have no moral equivalent in HDaudio, it's a Cadence-specific  IP.

Also there is already a degree of freedom in the allocation of
stream_tag, which is used for DMA support. That one makes sense since
DMAs may be used for non-SoundWire things (HDMI, trace, probe, etc).

That's 2 degrees of freedom on 3 levels, do you really need full
configurability?