Fix delayed start with rate plugin

Add the internal start_pending state in the rate plugin for supporting
delayed start in the case no data is committed to slave PCM.

This fixes the problem of CPU hog with artsd.

diff --git a/src/pcm/pcm_rate.c b/src/pcm/pcm_rate.c
index 3c65e2cae5e1a3269ae445f69e7eca232e6c0a7b..0403e5271c53c2d97f806d18c1ceb38c6af19264 100644 (file)
--- a/src/pcm/pcm_rate.c
+++ b/src/pcm/pcm_rate.c
@@ -68,6 +68,8 @@ struct _snd_pcm_rate {
        unsigned int put_idx;
        int16_t *src_buf;
        int16_t *dst_buf;
+       int start_pending; /* start is triggered but not commited to slave */
+       snd_htimestamp_t trigger_tstamp;
 };
 
 #endif /* DOC_HIDDEN */
@@ -408,6 +410,7 @@ static int snd_pcm_rate_init(snd_pcm_t *pcm)
        if (rate->ops.reset)
                rate->ops.reset(rate->obj);
        rate->last_commit_ptr = 0;
+       rate->start_pending = 0;
        return 0;
 }
 
@@ -797,7 +800,7 @@ static int snd_pcm_rate_commit_area(snd_pcm_t *pcm, snd_pcm_rate_t *rate,
                xfer = cont;
 
                if (xfer == slave_size)
-                       return 1;
+                       goto commit_done;
                
                /* commit second fragment */
                cont = slave_size - cont;
@@ -825,6 +828,13 @@ static int snd_pcm_rate_commit_area(snd_pcm_t *pcm, snd_pcm_rate_t *rate,
                        return 0;
                }
        }
+
+ commit_done:
+       if (rate->start_pending) {
+               /* we have pending start-trigger.  let's issue it now */
+               snd_pcm_start(rate->gen.slave);
+               rate->start_pending = 0;
+       }
        return 1;
 }
 
@@ -1083,6 +1093,41 @@ static int snd_pcm_rate_drain(snd_pcm_t *pcm)
        return snd_pcm_drain(rate->gen.slave);
 }
 
+static snd_pcm_state_t snd_pcm_rate_state(snd_pcm_t *pcm)
+{
+       snd_pcm_rate_t *rate = pcm->private_data;
+       if (rate->start_pending) /* pseudo-state */
+               return SND_PCM_STATE_RUNNING;
+       return snd_pcm_state(rate->gen.slave);
+}
+
+
+static int snd_pcm_rate_start(snd_pcm_t *pcm)
+{
+       snd_pcm_rate_t *rate = pcm->private_data;
+       snd_pcm_uframes_t avail;
+       struct timeval tv;
+               
+       if (pcm->stream == SND_PCM_STREAM_CAPTURE)
+               return snd_pcm_start(rate->gen.slave);
+
+       if (snd_pcm_state(rate->gen.slave) != SND_PCM_STATE_PREPARED)
+               return -EBADFD;
+
+       gettimeofday(&tv, 0);
+       rate->trigger_tstamp.tv_sec = tv.tv_sec;
+       rate->trigger_tstamp.tv_nsec = tv.tv_usec * 1000L;
+
+       avail = snd_pcm_mmap_playback_hw_avail(rate->gen.slave);
+       if (avail == 0) {
+               /* postpone the trigger since we have no data committed yet */
+               rate->start_pending = 1;
+               return 0;
+       }
+       rate->start_pending = 0;
+       return snd_pcm_start(rate->gen.slave);
+}
+
 static int snd_pcm_rate_status(snd_pcm_t *pcm, snd_pcm_status_t * status)
 {
        snd_pcm_rate_t *rate = pcm->private_data;
@@ -1096,6 +1141,11 @@ static int snd_pcm_rate_status(snd_pcm_t *pcm, snd_pcm_status_t * status)
                snd_atomic_read_ok(&ratom);
                return err;
        }
+       if (pcm->stream == SND_PCM_STREAM_PLAYBACK) {
+               if (rate->start_pending)
+                       status->state = SND_PCM_STATE_RUNNING;
+               status->trigger_tstamp = rate->trigger_tstamp;
+       }
        snd_pcm_rate_sync_hwptr(pcm);
        status->appl_ptr = *pcm->appl.ptr;
        status->hw_ptr = *pcm->hw.ptr;
@@ -1144,12 +1194,12 @@ static int snd_pcm_rate_close(snd_pcm_t *pcm)
 
 static snd_pcm_fast_ops_t snd_pcm_rate_fast_ops = {
        .status = snd_pcm_rate_status,
-       .state = snd_pcm_generic_state,
+       .state = snd_pcm_rate_state,
        .hwsync = snd_pcm_rate_hwsync,
        .delay = snd_pcm_rate_delay,
        .prepare = snd_pcm_rate_prepare,
        .reset = snd_pcm_rate_reset,
-       .start = snd_pcm_generic_start,
+       .start = snd_pcm_rate_start,
        .drop = snd_pcm_generic_drop,
        .drain = snd_pcm_rate_drain,
        .pause = snd_pcm_generic_pause,