| Message ID | 20240507133551.607171-1-perex@perex.cz (mailing list archive) |
|---|---|
| Headers | show |
| Series | ALSA: pcm: reinvent the stream synchronization ID API | expand |
On Tue, 07 May 2024 15:30:49 +0200, Jaroslav Kysela wrote: > > Until the commit e11f0f90a626 ("ALSA: pcm: remove SNDRV_PCM_IOCTL1_INFO > internal command"), there was a possibility to pass information > about the synchronized streams to the user space. The mentioned > commit removed blindly the appropriate code with an irrelevant comment. > > The revert may be appropriate, but since this API was lost for several > years without any complains, it's time to improve it. The hardware > parameters may change the used stream clock source (e.g. USB hardware) > so move this synchronization ID to hw_params as read-only field. > > It seems that pipewire can benefit from this API (disable adaptive > resampling for perfectly synchronized PCM streams) now. > > v3->v4: > - more code shuffle as suggested by Takashi > - remove unused snd_pcm_empty function in the second patch > - put back snd_pcm_set_sync documentation > > v2->v3: > - fix pcm_sync_empty() function (wrong comparison) [thanks Takashi Sakamoto] > - more documentation for snd_pcm_set_sync_per_card (ID composition) > > v1->v2: > - remove union usage per Takashi's request > - reduce memory usage > - use standard ID generation scheme > > Jaroslav Kysela (2): > ALSA: pcm: reinvent the stream synchronization ID API > ALSA: pcm: optimize and clarify stream sychronization ID API Do people have any concerns about this proposal? Otherwise I'm going to merge them for 6.11. thanks, Takashi
Until the commit e11f0f90a626 ("ALSA: pcm: remove SNDRV_PCM_IOCTL1_INFO internal command"), there was a possibility to pass information about the synchronized streams to the user space. The mentioned commit removed blindly the appropriate code with an irrelevant comment. The revert may be appropriate, but since this API was lost for several years without any complains, it's time to improve it. The hardware parameters may change the used stream clock source (e.g. USB hardware) so move this synchronization ID to hw_params as read-only field. It seems that pipewire can benefit from this API (disable adaptive resampling for perfectly synchronized PCM streams) now. v3->v4: - more code shuffle as suggested by Takashi - remove unused snd_pcm_empty function in the second patch - put back snd_pcm_set_sync documentation v2->v3: - fix pcm_sync_empty() function (wrong comparison) [thanks Takashi Sakamoto] - more documentation for snd_pcm_set_sync_per_card (ID composition) v1->v2: - remove union usage per Takashi's request - reduce memory usage - use standard ID generation scheme Jaroslav Kysela (2): ALSA: pcm: reinvent the stream synchronization ID API ALSA: pcm: optimize and clarify stream sychronization ID API include/sound/pcm.h | 17 +++++++++++-- include/uapi/sound/asound.h | 13 +++------- sound/core/pcm_lib.c | 50 +++++++++++++++++++++++++++++-------- sound/core/pcm_native.c | 6 +++++ sound/pci/emu10k1/p16v.c | 17 +++++++++---- 5 files changed, 77 insertions(+), 26 deletions(-)