When the hardware can only deal with a monotonically increasing appl_ptr, this flag can be set. In case the application requests a rewind, snd_pcm_rewind() will not return an error code but signal that the appl_ptr was not modified. Reviewed-by: Péter Ujfalusi <peter.ujfalusi@xxxxxxxxxxxxxxx> Reviewed-by: Kai Vehmanen <kai.vehmanen@xxxxxxxxxxxxxxx> Reviewed-by: Ranjani Sridharan <ranjani.sridharan@xxxxxxxxxxxxxxx> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> --- include/uapi/sound/asound.h | 2 +- sound/core/pcm_native.c | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h index 1d84ec9db93b..bdb6f3c9db6c 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 */ diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index d233cb3b41d8..e3da2cc31a34 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -2905,6 +2905,8 @@ static snd_pcm_sframes_t snd_pcm_rewind(struct snd_pcm_substream *substream, if (frames == 0) return 0; + if (substream->runtime->info & SNDRV_PCM_INFO_NO_REWINDS) + return 0; snd_pcm_stream_lock_irq(substream); ret = do_pcm_hwsync(substream); -- 2.25.1
