svn commit: r340350 - stable/12/sys/dev/sound/usb

[Hans Petter Selasky]

Author: hselasky
Date: Sun Nov 11 12:31:27 2018
New Revision: 340350
URL: https://svnweb.freebsd.org/changeset/base/340350

Log:
  MFC r340248:
  Don't read the USB audio sync endpoint when we don't use it to save
  isochronous bandwidth.
  
  Approved by:		re (kib)
  Sponsored by:		Mellanox Technologies

Modified:
  stable/12/sys/dev/sound/usb/uaudio.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/dev/sound/usb/uaudio.c
==============================================================================
--- stable/12/sys/dev/sound/usb/uaudio.c	Sun Nov 11 06:49:05 2018	(r340349)
+++ stable/12/sys/dev/sound/usb/uaudio.c	Sun Nov 11 12:31:27 2018	(r340350)
@@ -100,7 +100,7 @@ static int uaudio_default_channels = 0;		/* use defaul
 static int uaudio_buffer_ms = 8;
 
 #ifdef USB_DEBUG
-static int uaudio_debug = 0;
+static int uaudio_debug;
 
 static SYSCTL_NODE(_hw_usb, OID_AUTO, uaudio, CTLFLAG_RW, 0, "USB uaudio");
 
@@ -136,6 +136,8 @@ uaudio_buffer_ms_sysctl(SYSCTL_HANDLER_ARGS)
 SYSCTL_PROC(_hw_usb_uaudio, OID_AUTO, buffer_ms, CTLTYPE_INT | CTLFLAG_RWTUN,
     0, sizeof(int), uaudio_buffer_ms_sysctl, "I",
     "uaudio buffering delay from 2ms to 8ms");
+#else
+#define	uaudio_debug 0
 #endif
 
 #define	UAUDIO_NFRAMES		64	/* must be factor of 8 due HS-USB */
@@ -2161,6 +2163,14 @@ uaudio_chan_play_sync_callback(struct usb_xfer *xfer, 
 		break;
 
 	case USB_ST_SETUP:
+		/*
+		 * Check if the recording stream can be used as a
+		 * source of jitter information to save some
+		 * isochronous bandwidth:
+		 */
+		if (ch->priv_sc->sc_rec_chan.num_alt != 0 &&
+		    uaudio_debug == 0)
+			break;
 		usbd_xfer_set_frames(xfer, 1);
 		usbd_xfer_set_frame_len(xfer, 0, usbd_xfer_max_framelen(xfer));
 		usbd_transfer_submit(xfer);