The hw_base will be increased by runtime->buffer_size frames unconditionally if the runtime->status->hw_ptr is not updated for over half of buffer time. As the hw_base increases, so does the runtime->status->hw_ptr which could lead to invalid return value when user space program calls snd_pcm_avail() function.
By updating runtime->hw_ptr_jiffies each time the HWSYNC is called, the hw_base will keep the same when buffer stall happens, so does the hw_ptr.
Signed-off-by: Brent Lu brent.lu@intel.com --- sound/core/pcm_lib.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 872a852..d531e1b 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -433,6 +433,7 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
no_delta_check: if (runtime->status->hw_ptr == new_hw_ptr) { + runtime->hw_ptr_jiffies = curr_jiffies; update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp); return 0; }