diff options
| author | Pierre-Louis Bossart | 2021-11-19 17:08:50 -0600 |
|---|---|---|
| committer | Mark Brown | 2021-11-24 12:57:18 +0000 |
| commit | b456abe63f60ad93c83a526d33b71574bc32656c (patch) | |
| tree | 94c85af14b3d80371e201924a4209673f2723423 /include/uapi/sound | |
| parent | 0e888a74e52db369e19aec908131cf171079b306 (diff) | |
ALSA: pcm: introduce INFO_NO_REWINDS flag
When the hardware can only deal with a monotonically increasing
appl_ptr, this flag can be set.
In case the application requests a rewind, be it with a
snd_pcm_rewind() or with a direct change of a mmap'ed pointer followed
by a SNDRV_PCM_IOCTL_SYNC_PTR, this patch checks if a rewind
occurred and returns an error.
Credits to Takashi Iwai for identifying the path with SYNC_PTR and
suggesting the pointer checks.
Suggested-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20211119230852.206310-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'include/uapi/sound')
| -rw-r--r-- | include/uapi/sound/asound.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h index 5fbb79e30819..ff7e638221c5 100644 --- a/include/uapi/sound/asound.h +++ b/include/uapi/sound/asound.h @@ -300,7 +300,7 @@ typedef int __bitwise snd_pcm_subformat_t; #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_NO_REWINDS 0x20000000 /* hardware can only support monotonic changes of appl_ptr */ #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 */ |