From: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com
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@linux.intel.com Signed-off-by: Subhransu S. Prusty subhransu.s.prusty@intel.com --- 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); }