From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Enable no_period_wake and report max_inflight_bytes.
The estimate is a worst-case, it could be refined based on
actual number of packets per URB and total URBs, however this
information is only available in the prepare step
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@xxxxxxxxx>
---
sound/usb/pcm.c | 30 ++++++++++++++++++++++++++----
1 file changed, 26 insertions(+), 4 deletions(-)
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 44d178e..5bcc729 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -713,7 +713,8 @@ static int configure_endpoint(struct snd_usb_substream *subs)
static int snd_usb_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *hw_params)
{
- struct snd_usb_substream *subs = substream->runtime->private_data;
+ struct snd_pcm_runtime *runtime = substream->runtime;
+ struct snd_usb_substream *subs = runtime->private_data;
struct audioformat *fmt;
int ret;
@@ -728,7 +729,6 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
subs->buffer_periods = params_periods(hw_params);
subs->channels = params_channels(hw_params);
subs->cur_rate = params_rate(hw_params);
-
fmt = find_format(subs);
if (!fmt) {
dev_dbg(&subs->dev->dev,
@@ -749,6 +749,26 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
subs->altset_idx = fmt->altset_idx;
subs->need_setup_ep = true;
+ /*
+ * worst-case max_inflight_bytes is one URB (MAX_PACKS ms),
+ * multiply by size of 1ms packet for this format. The delay
+ * can be larger since there are up to MAX_URBS submitted,
+ * we only track the max number of bytes transferred when one
+ * URB is submitted.
+ */
+ runtime->hw.max_inflight_bytes = DIV_ROUND_UP(
+ MAX_PACKS * subs->cur_rate * subs->channels *
+ snd_pcm_format_width(subs->pcm_format), 8 * 1000);
+
+ /*
+ * The number of packets cannot exceed the ring buffer size, reflect
+ * constraints for low-latency usages
+ */
+ if (runtime->hw.max_inflight_bytes >
+ subs->period_bytes * subs->buffer_periods)
+ runtime->hw.max_inflight_bytes =
+ subs->period_bytes * subs->buffer_periods;
+
return 0;
}
@@ -851,6 +871,7 @@ static struct snd_pcm_hardware snd_usb_hardware =
.info = SNDRV_PCM_INFO_MMAP |
SNDRV_PCM_INFO_MMAP_VALID |
SNDRV_PCM_INFO_BATCH |
+ SNDRV_PCM_INFO_NO_PERIOD_WAKEUP |
SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_BLOCK_TRANSFER |
SNDRV_PCM_INFO_PAUSE,
@@ -1225,6 +1246,7 @@ static int snd_usb_pcm_open(struct snd_pcm_substream *substream, int direction)
subs->interface = -1;
subs->altset_idx = 0;
runtime->hw = snd_usb_hardware;
+ runtime->hw.max_inflight_bytes = 0; /* will be set in hw_params() */
runtime->private_data = subs;
subs->pcm_substream = substream;
/* runtime PM is also done there */
@@ -1328,7 +1350,7 @@ static void retire_capture_urb(struct snd_usb_substream *subs,
}
}
- if (period_elapsed)
+ if (period_elapsed && !runtime->no_period_wakeup)
snd_pcm_period_elapsed(subs->pcm_substream);
}
@@ -1542,7 +1564,7 @@ static void prepare_playback_urb(struct snd_usb_substream *subs,
spin_unlock_irqrestore(&subs->lock, flags);
urb->transfer_buffer_length = bytes;
- if (period_elapsed)
+ if (period_elapsed && !runtime->no_period_wakeup)
snd_pcm_period_elapsed(subs->pcm_substream);
}
--
1.9.1
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