From: Jaroslav Kysela <perex@perex.cz>
To: <linux-sound@vger.kernel.org>
Cc: Takashi Iwai <tiwai@suse.de>, Jaroslav Kysela <perex@perex.cz>
Subject: [PATCH v3 0/2] ALSA: pcm: reinvent the stream synchronization ID API
Date: Tue, 7 May 2024 10:26:17 +0200 [thread overview]
Message-ID: <20240507083142.557299-1-perex@perex.cz> (raw)
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.
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 | 19 ++++++++++++--
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, 79 insertions(+), 26 deletions(-)
--
2.43.0
next reply other threads:[~2024-05-07 8:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-07 8:26 Jaroslav Kysela [this message]
2024-05-07 8:26 ` [PATCH v3 1/2] ALSA: pcm: reinvent the stream synchronization ID API Jaroslav Kysela
2024-05-07 12:33 ` Takashi Iwai
2024-05-07 8:26 ` [PATCH v3 2/2] ALSA: pcm: optimize and clarify stream sychronization " Jaroslav Kysela
2024-05-07 12:38 ` Takashi Iwai
2024-05-07 12:40 ` [PATCH v3 0/2] ALSA: pcm: reinvent the stream synchronization " Takashi Iwai
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