[alsa-devel] Fwd: ALSA queries

[Takashi Iwai]

On Tue, 07 Aug 2018 13:59:46 +0200,
Chakravarthi Pradeep wrote:
> 
> Dear Takashi,
> 
> Trigger stop is getting called , because of this hwptr is zero and
> pointer call back is not getting called. Below is my log from driver.
> 
> [  838.491681] Trigger:Start
> [  839.522233] hwptr=0 buf_pos:3456
> [  839.522244] buf_pos :3456 bytes_to_frames:864 uhdc_audio_pcm_pointer_253
> [  839.522249] Trigger:Stop

Then you need to figure out the code path of the trigger stop.

> In normal scenario, Trigger stop is not getting called and audio was
> able to render in the VLC application. Below log for normal scenario,
> [  802.785893] Trigger:Start
> [  814.288309] hwptr=0 buf_pos:6272
> [  814.288323] buf_pos :6272 bytes_to_frames:1568 uhdc_audio_pcm_pointer_253
> [  814.288362] buf_pos :6272 bytes_to_frames:1568 uhdc_audio_pcm_pointer_253
> [  814.288378] buf_pos :6272 bytes_to_frames:1568 uhdc_audio_pcm_pointer_253
> [  814.305079] hwptr=6272 buf_pos:9472
> [  814.305091] buf_pos :9472 bytes_to_frames:2368 uhdc_audio_pcm_pointer_253
> [  814.321741] hwptr=9472 buf_pos:12672
> [  814.321748] buf_pos :12672 bytes_to_frames:3168 uhdc_audio_pcm_pointer_253
> [  814.321777] buf_pos :12672 bytes_to_frames:3168 uhdc_audio_pcm_pointer_253
> [  814.321785] buf_pos :12672 bytes_to_frames:3168 uhdc_audio_pcm_pointer_253
> [  814.338452] hwptr=12672 buf_pos:15872
> [  814.338459] buf_pos :15872 bytes_to_frames:3968 uhdc_audio_pcm_pointer_253
> [  814.355242] hwptr=15872 buf_pos:19072
> [  814.355248] buf_pos :19072 bytes_to_frames:4768 uhdc_audio_pcm_pointer_253
> [  814.355288] buf_pos :19072 bytes_to_frames:4768 uhdc_audio_pcm_pointer_253
> [  814.355294] buf_pos :19072 bytes_to_frames:4768 uhdc_audio_pcm_pointer_253
> [  814.371822] hwptr=19072 buf_pos:22272
> ...
> ...
> [  830.739031] Trigger:Stop
> 
> 
> I can not do rmmod for ALSA driver. If I do sudo rmmod mydriver then it says
> "rmmod: ERROR: Module mydriver is in use"
> 
> How can I remove mydriver module from linux kernel ?

Likely some program is using the sound device.  For example, a mixer
applet or PulseAudio keeps opening the control device.
Check it via "fuser -v /dev/snd/*"


Takashi