| Message ID | 20240506151218.377580-1-perex@perex.cz (mailing list archive) |
|---|---|
| Headers | show |
| Series | ALSA: pcm: reinvent the stream synchronization ID API | expand |
On Mon, May 06, 2024 at 05:11:48PM +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. > > 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 | 18 ++++++++++++++++-- > include/uapi/sound/asound.h | 13 ++++--------- > sound/core/pcm_lib.c | 36 ++++++++++++++++++++++++++---------- > sound/core/pcm_native.c | 6 ++++++ > sound/pci/emu10k1/p16v.c | 17 ++++++++++++----- > 5 files changed, 64 insertions(+), 26 deletions(-) I reviewed and added some comments per each. Anyway, we are at the last week of kernel development process. I think it better to postpone the discussion about this kind of changes until releasing -rc1, if people working for the task of quality assurance to the new kernel release. Regards Takashi (not this subsystem maintainer) Sakamoto
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. 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 | 18 ++++++++++++++++-- include/uapi/sound/asound.h | 13 ++++--------- sound/core/pcm_lib.c | 36 ++++++++++++++++++++++++++---------- sound/core/pcm_native.c | 6 ++++++ sound/pci/emu10k1/p16v.c | 17 ++++++++++++----- 5 files changed, 64 insertions(+), 26 deletions(-)