At Tue, 07 Oct 2008 17:32:05 +0200,
I wrote:
>
> Hi,
>
> the patch below (to the latest sound git tree) adds the extra delay
> count for USB-audio driver. This change will appear as the return
> value of snd_pcm_delay().
>
> Could you check whether it's appropriate behavior you've wanted?
Ping.
Takashi
>
>
> thanks,
>
> Takashi
>
> diff --git a/include/sound/pcm.h b/include/sound/pcm.h
> index 40c5a6f..dcbdc60 100644
> --- a/include/sound/pcm.h
> +++ b/include/sound/pcm.h
> @@ -269,6 +269,7 @@ struct snd_pcm_runtime {
> snd_pcm_uframes_t avail_max;
> snd_pcm_uframes_t hw_ptr_base; /* Position at buffer restart */
> snd_pcm_uframes_t hw_ptr_interrupt; /* Position at interrupt time*/
> + 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 e61e125..df7c3fa 100644
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -597,14 +597,15 @@ 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;
> }
> @@ -2423,6 +2424,7 @@ 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;
> diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
> index 6e70ba4..7d5a103 100644
> --- a/sound/usb/usbaudio.c
> +++ b/sound/usb/usbaudio.c
> @@ -629,6 +629,7 @@ static int prepare_playback_urb(struct snd_usb_substream *subs,
> subs->hwptr_done += offs;
> if (subs->hwptr_done >= runtime->buffer_size)
> subs->hwptr_done -= runtime->buffer_size;
> + runtime->delay += offs;
> spin_unlock_irqrestore(&subs->lock, flags);
> urb->transfer_buffer_length = offs * stride;
> if (period_elapsed)
> @@ -638,12 +639,20 @@ static int prepare_playback_urb(struct snd_usb_substream *subs,
>
> /*
> * process after playback data complete
> - * - nothing to do
> + * - decrease the delay count again
> */
> static int retire_playback_urb(struct snd_usb_substream *subs,
> struct snd_pcm_runtime *runtime,
> struct urb *urb)
> {
> + unsigned long flags;
> + int stride = runtime->frame_bits >> 3;
> + int processed = urb->transfer_buffer_length / stride;
> +
> + spin_lock_irqsave(&subs->lock, flags);
> + if (processed > runtime->delay)
> + runtime->delay -= processed;
> + spin_unlock_irqrestore(&subs->lock, flags);
> return 0;
> }
>
> @@ -1542,6 +1551,7 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
> subs->hwptr_done = 0;
> subs->transfer_done = 0;
> subs->phase = 0;
> + runtime->delay = 0;
>
> /* clear urbs (to be sure) */
> deactivate_urbs(subs, 0, 1);
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