Re: [PATCH 1/3] soundwire: qcom: drop unneeded DAI .set_stream callback

[Krzysztof Kozlowski]

On 25/10/2023 17:12, Pierre-Louis Bossart wrote:
> 
> 
> On 10/25/23 09:45, Krzysztof Kozlowski wrote:
>> Qualcomm Soundwire controller drivers do not support multi-link setups,
>> so DAI .set_stream() callback will not be used.  What's more, if called
>> it will overwrite the sdw_stream_runtime runtime set in DAI .startup
>> (qcom_swrm_startup()) causing issues (unsupported multi-link error) when
>> two Soundwire controllers are passed as codec DAIs.
> 
> This last sentence is confusing at best.
> 
> A controller can have one or more managers, each of whom can have one or
> more peripherals.
> 
> only peripherals should expose codec DAIs, managers should expose CPU DAIs.
> 
> Put differently, the controller is the host part while the peripheral is
> the codec part. "controllers passed as codec DAIs" is not really
> possible, or this was a typo?

No, it wasn't a typo. Take a look here:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts#n1023

The <&swr0 0> is the controller, although probably I should call it
manager, but in case of Qualcomm I think they are 1-to-1.

Best regards,
Krzysztof