alsa-project/alsa-lib issue #264 was opened from chihhao-chen:

I am testing many types of headsets on Android platform with different kernel versions.

On kernel-5.10, calling sequence before playback is snd_usb_hw_params -> set highest sampling rate, no SAMPLING_FREQ_CONTROL USB request in this stage snd_pcm_release snd_usb_hw_params -> set proper sampling rate, still no SAMPLING_FREQ_CONTROL USB request snd_usb_pcm_parepare -> in configure_endpoint SAMPLING_FREQ_CONTROL USB request was sent

With the same calling sequence, a slightly behavior change on kernel-5.15 is snd_usb_hw_params -> set highest sampling rate, SAMPLING_FREQ_CONTROL USB request was sent snd_pcm_release snd_usb_hw_params -> set proper sampling rate, SAMPLING_FREQ_CONTROL USB request was sent too (because configure_endpoint was moved to snd_usb_hw_params function) snd_usb_pcm_parepare -> no SAMPLING_FREQ_CONTROL USB request because of USB EP flag check

I checked all USB packets and confirmed audio data output was correct. But there may be missing sound problem for the first sound with many headsets (for example Samsung headset). I found this issue is related to two-times sampling rate set request. (I tried forcibly skip first USB request, everything became okay.) So do you guys know why configure_endpoint was moved to snd_usb_hw_params? Or could you provide patch for this problem?

Many thanks Chihhao

Issue URL : https://github.com/alsa-project/alsa-lib/issues/264 Repository URL: https://github.com/alsa-project/alsa-lib