ALSA: Add extra delay count in PCM

Added runtime->delay field to adjust the delayed samples for snd_pcm_delay().
Typically a hardware FIFO length is stored in this field, so that the
extra delay between hwptr and applptr can be computed.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 6 insertions, 3 deletions

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index c17296891617..267effddb070 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -270,6 +270,7 @@ struct snd_pcm_runtime {
         snd_pcm_uframes_t hw_ptr_base;  /* Position at buffer restart */
         snd_pcm_uframes_t hw_ptr_interrupt; /* Position at interrupt time */
         unsigned long hw_ptr_jiffies;   /* Time when hw_ptr is updated */
+        snd_pcm_sframes_t delay;        /* extra delay; typically FIFO size */
 
         /* -- HW params -- */
         snd_pcm_access_t access;        /* access mode */
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index fc6f98e257df..cb769d415db7 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -587,14 +587,15 @@ int snd_pcm_status(struct snd_pcm_substream *substream,
         if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
                 status->avail = snd_pcm_playback_avail(runtime);
                 if (runtime->status->state == SNDRV_PCM_STATE_RUNNING ||
-                    runtime->status->state == SNDRV_PCM_STATE_DRAINING)
+                    runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
                         status->delay = runtime->buffer_size - status->avail;
-                else
+                        status->delay += runtime->delay;
+                } else
                         status->delay = 0;
         } else {
                 status->avail = snd_pcm_capture_avail(runtime);
                 if (runtime->status->state == SNDRV_PCM_STATE_RUNNING)
-                        status->delay = status->avail;
+                        status->delay = status->avail + runtime->delay;
                 else
                         status->delay = 0;
         }
@@ -2404,6 +2405,7 @@ static int snd_pcm_delay(struct snd_pcm_substream *substream,
                         n = snd_pcm_playback_hw_avail(runtime);
                 else
                         n = snd_pcm_capture_avail(runtime);
+                n += runtime->delay;
                 break;
         case SNDRV_PCM_STATE_XRUN:
                 err = -EPIPE;