参照元

説明

引数

返り値

参考

実装

/*
 * Wait until avail_min data becomes available
 * Returns a negative error code if any error occurs during operation.
 * The available space is stored on availp.  When err = 0 and avail = 0
 * on the capture stream, it indicates the stream is in DRAINING state.
 */
static int wait_for_avail_min(struct snd_pcm_substream *substream,
			      snd_pcm_uframes_t *availp)
{
	struct snd_pcm_runtime *runtime = substream->runtime;
	int is_playback = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
	wait_queue_t wait;
	int err = 0;
	snd_pcm_uframes_t avail = 0;
	long tout;
	init_waitqueue_entry(&wait, current);
	add_wait_queue(&runtime->sleep, &wait);
	for (;;) {
		if (signal_pending(current)) {
			err = -ERESTARTSYS;
			break;
		}
		set_current_state(TASK_INTERRUPTIBLE);
		snd_pcm_stream_unlock_irq(substream);
		tout = schedule_timeout(msecs_to_jiffies(10000));
		snd_pcm_stream_lock_irq(substream);
		switch (runtime->status->state) {
		case SNDRV_PCM_STATE_SUSPENDED:
			err = -ESTRPIPE;
			goto _endloop;
		case SNDRV_PCM_STATE_XRUN:
			err = -EPIPE;
			goto _endloop;
		case SNDRV_PCM_STATE_DRAINING:
			if (is_playback)
				err = -EPIPE;
			else 
				avail = 0; /* indicate draining */
			goto _endloop;
		case SNDRV_PCM_STATE_OPEN:
		case SNDRV_PCM_STATE_SETUP:
		case SNDRV_PCM_STATE_DISCONNECTED:
			err = -EBADFD;
			goto _endloop;
		}
		if (!tout) {
			snd_printd("%s write error (DMA or IRQ trouble?)\n",
				   is_playback ? "playback" : "capture");
			err = -EIO;
			break;
		}
		if (is_playback)
			avail = snd_pcm_playback_avail(runtime);
		else
			avail = snd_pcm_capture_avail(runtime);
		if (avail >= runtime->control->avail_min)
			break;
	}
 _endloop:
	remove_wait_queue(&runtime->sleep, &wait);
	*availp = avail;
	return err;
}

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Last-modified: 2014-09-13 (土) 08:26:44