diff options
| author | Takashi Iwai | 2021-08-13 10:21:42 +0200 |
|---|---|---|
| committer | Takashi Iwai | 2021-08-14 08:38:25 +0200 |
| commit | 81be10934949da8b12ca4db3de1511a4220fa9b4 (patch) | |
| tree | 282becbe725c64226c35fd947eaa9919f8a6b911 /include/uapi | |
| parent | 7ac2246f5670f42a3aac3eb05d23112f6ecfd4de (diff) | |
ALSA: pcm: Add SNDRV_PCM_INFO_EXPLICIT_SYNC flag
ALSA PCM core has an optimized way to communicate with user-space for
its control and status data via mmap on the supported architectures
like x86. Depending on the situation, however, we'd rather want to
enforce user-space notifying the applptr or hwptr change explicitly
via ioctl. For example, the upcoming non-contig and non-coherent
buffer handling would need an explicit sync, and this needs to catch
the applptr and hwptr changes. Also, ASoC SOF driver will have the
SPIB support that has the similar requirement for the explicit control
of the applptr and hwptr.
This patch adds the new PCM hardware info flag,
SNDRV_PCM_INFO_EXPLICIT_SYNC. When this flag is set, PCM core
disables both the control and the status mmap, which enforces
user-space to update via SYNC_PTR ioctl. In that way, drivers can
catch the applptr and hwptr update and apply the sync operation if
needed.
Link: https://lore.kernel.org/r/20210812113818.6479-1-tiwai@suse.de
Link: https://lore.kernel.org/r/20210610205326.1176400-1-pierre-louis.bossart@linux.intel.com
Link: https://lore.kernel.org/r/20210813082142.5375-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/sound/asound.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h index d17c061950df..1d84ec9db93b 100644 --- a/include/uapi/sound/asound.h +++ b/include/uapi/sound/asound.h @@ -299,6 +299,7 @@ typedef int __bitwise snd_pcm_subformat_t; #define SNDRV_PCM_INFO_HAS_LINK_ABSOLUTE_ATIME 0x02000000 /* report absolute hardware link audio time, not reset on startup */ #define SNDRV_PCM_INFO_HAS_LINK_ESTIMATED_ATIME 0x04000000 /* report estimated link audio time */ #define SNDRV_PCM_INFO_HAS_LINK_SYNCHRONIZED_ATIME 0x08000000 /* report synchronized audio/system time */ +#define SNDRV_PCM_INFO_EXPLICIT_SYNC 0x10000000 /* needs explicit sync of pointers and data */ #define SNDRV_PCM_INFO_DRAIN_TRIGGER 0x40000000 /* internal kernel flag - trigger in drain */ #define SNDRV_PCM_INFO_FIFO_IN_FRAMES 0x80000000 /* internal kernel flag - FIFO size is in frames */ |