AUDIO - Flow control not working with only 1 supported sample-rate

[gmikitiuk]

Operating System

Windows 10

Board

Custom design

Firmware

Modified uac2_headset example

What happened ?

I've noticed that whenever only one sampling frequency is available in sample_rates, Windows stops asking for current frequency and this is the only way(to my knowledge) to get sample_rate_tx initialized which leads to no flow control working(due to uninitialized sample_rate_tx.

How to reproduce ?

Configure a single frequency in sample_rates.

Debug Log as txt file (LOG/CFG_TUSB_DEBUG=2)

No logs possible with my host

Screenshots

No response

I have checked existing issues, dicussion and documentation

• [X] I confirm I have checked existing issues, dicussion and documentation.

[HiFiPhile]

Never tried this case, Windows neither get nor set sample rate ?

[gmikitiuk]

I didn't check it, as in my use-case sample rate is fixed, so it's marked as read only in descriptor. I don't even expect a set call. What is sure is that get is never called if only one sample rate is available(I guess it assumes that it must be the one presented in the list).

I've worked around it by providing two sample rates but no ability to change it.

[HiFiPhile]

I took a look and couldn't reproduce the issue with audio_4_channel_mic example where sample rate is fixed and marked as read only in descriptor.

When sample rate is read-only Windows won't call set sample rate, but get sample rate is always called before streaming start.