+/*
+ * Prepare urb for streaming before playback starts.
+ *
+ * We don't care about (or have) any data, so we just send a transfer delimiter.
+ */
+static int prepare_startup_playback_urb(struct snd_usb_substream *subs,
+ struct snd_pcm_runtime *runtime,
+ struct urb *urb)
+{
+ unsigned int i;
+ struct snd_urb_ctx *ctx = urb->context;
+
+ 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;
+ }
+ urb->transfer_buffer_length = 0;
+ return 0;
+}
+