From 40510d19054078235804601131db308e312feaec Mon Sep 17 00:00:00 2001
From: Clemens Ladisch <clemens@ladisch.de>
Date: Thu, 12 Jan 2006 08:17:49 +0100
Subject: [PATCH] --- yaml --- r: 19550 b: refs/heads/master c:
 4b2849283461a64c6d8cc6c7e72c62d7b4d91b43 h: refs/heads/master v: v3

---
 [refs]                     |  2 +-
 trunk/sound/usb/usbaudio.c | 26 +++++++++++++++++++++-----
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/[refs] b/[refs]
index 02af1fd23b83..b368d5e65020 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 54c63cfc153c6909a5d5dbe6072e8704b091f30e
+refs/heads/master: 4b2849283461a64c6d8cc6c7e72c62d7b4d91b43
diff --git a/trunk/sound/usb/usbaudio.c b/trunk/sound/usb/usbaudio.c
index a1bd8040dea4..95729730bcdc 100644
--- a/trunk/sound/usb/usbaudio.c
+++ b/trunk/sound/usb/usbaudio.c
@@ -478,22 +478,38 @@ static int retire_playback_sync_urb_hs(struct snd_usb_substream *subs,
 /*
  * Prepare urb for streaming before playback starts.
  *
- * We don't care about (or have) any data, so we just send a transfer delimiter.
+ * We don't yet have data, so we send a frame of silence.
  */
 static int prepare_startup_playback_urb(struct snd_usb_substream *subs,
 					struct snd_pcm_runtime *runtime,
 					struct urb *urb)
 {
-	unsigned int i;
+	unsigned int i, offs, counts;
 	struct snd_urb_ctx *ctx = urb->context;
+	int stride = runtime->frame_bits >> 3;
 
+	offs = 0;
 	urb->dev = ctx->subs->dev;
 	urb->number_of_packets = subs->packs_per_ms;
 	for (i = 0; i < subs->packs_per_ms; ++i) {
-		urb->iso_frame_desc[i].offset = 0;
-		urb->iso_frame_desc[i].length = 0;
+		/* calculate the size of a packet */
+		if (subs->fill_max)
+			counts = subs->maxframesize; /* fixed */
+		else {
+			subs->phase = (subs->phase & 0xffff)
+				+ (subs->freqm << subs->datainterval);
+			counts = subs->phase >> 16;
+			if (counts > subs->maxframesize)
+				counts = subs->maxframesize;
+		}
+		urb->iso_frame_desc[i].offset = offs * stride;
+		urb->iso_frame_desc[i].length = counts * stride;
+		offs += counts;
 	}
-	urb->transfer_buffer_length = 0;
+	urb->transfer_buffer_length = offs * stride;
+	memset(urb->transfer_buffer,
+	       subs->cur_audiofmt->format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0,
+	       offs * stride);
 	return 0;
 }