ALSA: Add USB US122L driver

Added a new US122L usb-audio driver.  This driver works together with a
dedicated alsa-lib plugin.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

1 files changed, 761 insertions, 0 deletions

diff --git a/sound/usb/usx2y/usb_stream.c b/sound/usb/usx2y/usb_stream.c
new file mode 100644
index 000000000000..ff23cc1ce3b9
--- /dev/null
+++ b/sound/usb/usx2y/usb_stream.c
@@ -0,0 +1,761 @@
+/*
+ * Copyright (C) 2007, 2008 Karsten Wiese <fzu@wemgehoertderstaat.de>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/usb.h>
+
+#include "usb_stream.h"
+
+
+/*                             setup                                  */
+
+static unsigned usb_stream_next_packet_size(struct usb_stream_kernel *sk)
+{
+	struct usb_stream *s = sk->s;
+	sk->out_phase_peeked = (sk->out_phase & 0xffff) + sk->freqn;
+	return (sk->out_phase_peeked >> 16) * s->cfg.frame_size;
+}
+
+static void playback_prep_freqn(struct usb_stream_kernel *sk, struct urb *urb)
+{
+	struct usb_stream *s = sk->s;
+	unsigned l = 0;
+	int pack;
+
+	urb->iso_frame_desc[0].offset = 0;
+	urb->iso_frame_desc[0].length =	usb_stream_next_packet_size(sk);
+	sk->out_phase = sk->out_phase_peeked;
+	urb->transfer_buffer_length = urb->iso_frame_desc[0].length;
+
+	for (pack = 1; pack < sk->n_o_ps; pack++) {
+		l = usb_stream_next_packet_size(sk);
+		if (s->idle_outsize + urb->transfer_buffer_length + l >
+		    s->period_size)
+			goto check;
+
+		sk->out_phase = sk->out_phase_peeked;
+		urb->iso_frame_desc[pack].offset = urb->transfer_buffer_length;
+		urb->iso_frame_desc[pack].length = l;
+		urb->transfer_buffer_length += l;
+	}
+	snd_printdd(KERN_DEBUG "%i\n", urb->transfer_buffer_length);
+
+check:
+	urb->number_of_packets = pack;
+	s->idle_outsize += urb->transfer_buffer_length - s->period_size;
+	snd_printdd(KERN_DEBUG "idle=%i ul=%i ps=%i\n", s->idle_outsize,
+		    urb->transfer_buffer_length, s->period_size);
+}
+
+static void init_pipe_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
+			   struct urb **urbs, char *transfer,
+			   struct usb_device *dev, int pipe)
+{
+	int u, p;
+	int maxpacket = use_packsize ?
+		use_packsize : usb_maxpacket(dev, pipe, usb_pipeout(pipe));
+	int transfer_length = maxpacket * sk->n_o_ps;
+
+	for (u = 0; u < USB_STREAM_NURBS;
+	     ++u, transfer += transfer_length) {
+		struct urb *urb = urbs[u];
+		struct usb_iso_packet_descriptor *desc;
+		urb->transfer_flags = URB_ISO_ASAP;
+		urb->transfer_buffer = transfer;
+		urb->dev = dev;
+		urb->pipe = pipe;
+		urb->number_of_packets = sk->n_o_ps;
+		urb->context = sk;
+		urb->interval = 1;
+		if (usb_pipeout(pipe))
+			continue;
+
+		urb->transfer_buffer_length = transfer_length;
+		desc = urb->iso_frame_desc;
+		desc->offset = 0;
+		desc->length = maxpacket;
+		for (p = 1; p < sk->n_o_ps; ++p) {
+			desc[p].offset = desc[p - 1].offset + maxpacket;
+			desc[p].length = maxpacket;
+		}
+	}
+}
+
+static void init_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
+		      struct usb_device *dev, int in_pipe, int out_pipe)
+{
+	struct usb_stream	*s = sk->s;
+	char			*indata = (char *)s + sizeof(*s) +
+					sizeof(struct usb_stream_packet) *
+					s->inpackets;
+	int			u;
+
+	for (u = 0; u < USB_STREAM_NURBS; ++u) {
+		sk->inurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
+		sk->outurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
+	}
+
+	init_pipe_urbs(sk, use_packsize, sk->inurb, indata, dev, in_pipe);
+	init_pipe_urbs(sk, use_packsize, sk->outurb, sk->write_page, dev,
+		       out_pipe);
+}
+
+
+/*
+ * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
+ * this will overflow at approx 524 kHz
+ */
+static inline unsigned get_usb_full_speed_rate(unsigned rate)
+{
+	return ((rate << 13) + 62) / 125;
+}
+
+/*
+ * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
+ * this will overflow at approx 4 MHz
+ */
+static inline unsigned get_usb_high_speed_rate(unsigned rate)
+{
+	return ((rate << 10) + 62) / 125;
+}
+
+void usb_stream_free(struct usb_stream_kernel *sk)
+{
+	struct usb_stream *s;
+	unsigned u;
+
+	for (u = 0; u < USB_STREAM_NURBS; ++u) {
+		usb_free_urb(sk->inurb[u]);
+		sk->inurb[u] = NULL;
+		usb_free_urb(sk->outurb[u]);
+		sk->outurb[u] = NULL;
+	}
+
+	s = sk->s;
+	if (!s)
+		return;
+
+	free_pages((unsigned long)sk->write_page, get_order(s->write_size));
+	sk->write_page = NULL;
+	free_pages((unsigned long)s, get_order(s->read_size));
+	sk->s = NULL;
+}
+
+struct usb_stream *usb_stream_new(struct usb_stream_kernel *sk,
+				  struct usb_device *dev,
+				  unsigned in_endpoint, unsigned out_endpoint,
+				  unsigned sample_rate, unsigned use_packsize,
+				  unsigned period_frames, unsigned frame_size)
+{
+	int packets, max_packsize;
+	int in_pipe, out_pipe;
+	int read_size = sizeof(struct usb_stream);
+	int write_size;
+	int usb_frames = dev->speed == USB_SPEED_HIGH ? 8000 : 1000;
+	int pg;
+
+	in_pipe = usb_rcvisocpipe(dev, in_endpoint);
+	out_pipe = usb_sndisocpipe(dev, out_endpoint);
+
+	max_packsize = use_packsize ?
+		use_packsize : usb_maxpacket(dev, in_pipe, 0);
+
+	/*
+		t_period = period_frames / sample_rate
+		iso_packs = t_period / t_iso_frame
+			= (period_frames / sample_rate) * (1 / t_iso_frame)
+	*/
+
+	packets = period_frames * usb_frames / sample_rate + 1;
+
+	if (dev->speed == USB_SPEED_HIGH)
+		packets = (packets + 7) & ~7;
+
+	read_size += packets * USB_STREAM_URBDEPTH *
+		(max_packsize + sizeof(struct usb_stream_packet));
+
+	max_packsize = usb_maxpacket(dev, out_pipe, 1);
+	write_size = max_packsize * packets * USB_STREAM_URBDEPTH;
+
+	if (read_size >= 256*PAGE_SIZE || write_size >= 256*PAGE_SIZE) {
+		snd_printk(KERN_WARNING "a size exceeds 128*PAGE_SIZE\n");
+		goto out;
+	}
+
+	pg = get_order(read_size);
+	sk->s = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
+	if (!sk->s) {
+		snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
+		goto out;
+	}
+	sk->s->cfg.version = USB_STREAM_INTERFACE_VERSION;
+
+	sk->s->read_size = read_size;
+
+	sk->s->cfg.sample_rate = sample_rate;
+	sk->s->cfg.frame_size = frame_size;
+	sk->n_o_ps = packets;
+	sk->s->inpackets = packets * USB_STREAM_URBDEPTH;
+	sk->s->cfg.period_frames = period_frames;
+	sk->s->period_size = frame_size * period_frames;
+
+	sk->s->write_size = write_size;
+	pg = get_order(write_size);
+
+	sk->write_page =
+		(void *)__get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
+	if (!sk->write_page) {
+		snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
+		usb_stream_free(sk);
+		return NULL;
+	}
+
+	/* calculate the frequency in 16.16 format */
+	if (dev->speed == USB_SPEED_FULL)
+		sk->freqn = get_usb_full_speed_rate(sample_rate);
+	else
+		sk->freqn = get_usb_high_speed_rate(sample_rate);
+
+	init_urbs(sk, use_packsize, dev, in_pipe, out_pipe);
+	sk->s->state = usb_stream_stopped;
+out:
+	return sk->s;
+}
+
+
+/*                             start                                  */
+
+static bool balance_check(struct usb_stream_kernel *sk, struct urb *urb)
+{
+	bool r;
+	if (unlikely(urb->status)) {
+		if (urb->status != -ESHUTDOWN && urb->status != -ENOENT)
+			snd_printk(KERN_WARNING "status=%i\n", urb->status);
+		sk->iso_frame_balance = 0x7FFFFFFF;
+		return false;
+	}
+	r = sk->iso_frame_balance == 0;
+	if (!r)
+		sk->i_urb = urb;
+	return r;
+}
+
+static bool balance_playback(struct usb_stream_kernel *sk, struct urb *urb)
+{
+	sk->iso_frame_balance += urb->number_of_packets;
+	return balance_check(sk, urb);
+}
+
+static bool balance_capture(struct usb_stream_kernel *sk, struct urb *urb)
+{
+	sk->iso_frame_balance -= urb->number_of_packets;
+	return balance_check(sk, urb);
+}
+
+static void subs_set_complete(struct urb **urbs, void (*complete)(struct urb *))
+{
+	int u;
+
+	for (u = 0; u < USB_STREAM_NURBS; u++) {
+		struct urb *urb = urbs[u];
+		urb->complete = complete;
+	}
+}
+
+int usb_stream_prepare_playback(struct usb_stream_kernel *sk, struct urb *inurb)
+{
+	struct usb_stream *s = sk->s;
+	struct urb *io;
+	struct usb_iso_packet_descriptor *id, *od;
+	int p, l = 0;
+
+	io = sk->idle_outurb;
+	od = io->iso_frame_desc;
+	io->transfer_buffer_length = 0;
+
+	for (p = 0; s->sync_packet < 0; ++p, ++s->sync_packet) {
+		struct urb *ii = sk->completed_inurb;
+		id = ii->iso_frame_desc +
+			ii->number_of_packets + s->sync_packet;
+		l = id->actual_length;
+
+		od[p].length = l;
+		od[p].offset = io->transfer_buffer_length;
+		io->transfer_buffer_length += l;
+	}
+
+	for (;
+	     s->sync_packet < inurb->number_of_packets && p < sk->n_o_ps;
+	     ++p, ++s->sync_packet) {
+		l = inurb->iso_frame_desc[s->sync_packet].actual_length;
+
+		if (s->idle_outsize + io->transfer_buffer_length + l >
+		    s->period_size)
+			goto check_ok;
+
+		od[p].length = l;
+		od[p].offset = io->transfer_buffer_length;
+		io->transfer_buffer_length += l;
+	}
+
+check_ok:
+	s->sync_packet -= inurb->number_of_packets;
+	if (s->sync_packet < -2 || s->sync_packet > 0) {
+		snd_printk(KERN_WARNING "invalid sync_packet = %i;"
+			   " p=%i nop=%i %i %x %x %x > %x\n",
+			   s->sync_packet, p, inurb->number_of_packets,
+			   s->idle_outsize + io->transfer_buffer_length + l,
+			   s->idle_outsize, io->transfer_buffer_length,  l,
+			   s->period_size);
+		return -1;
+	}
+	if (io->transfer_buffer_length % s->cfg.frame_size) {
+		snd_printk(KERN_WARNING"invalid outsize = %i\n",
+			   io->transfer_buffer_length);
+		return -1;
+	}
+	s->idle_outsize += io->transfer_buffer_length - s->period_size;
+	io->number_of_packets = p;
+	if (s->idle_outsize > 0) {
+		snd_printk(KERN_WARNING "idle=%i\n", s->idle_outsize);
+		return -1;
+	}
+	return 0;
+}
+
+static void prepare_inurb(int number_of_packets, struct urb *iu)
+{
+	struct usb_iso_packet_descriptor *id;
+	int p;
+
+	iu->number_of_packets = number_of_packets;
+	id = iu->iso_frame_desc;
+	id->offset = 0;
+	for (p = 0; p < iu->number_of_packets - 1; ++p)
+		id[p + 1].offset = id[p].offset + id[p].length;
+
+	iu->transfer_buffer_length =
+		id[0].length * iu->number_of_packets;
+}
+
+static int submit_urbs(struct usb_stream_kernel *sk,
+		       struct urb *inurb, struct urb *outurb)
+{
+	int err;
+	prepare_inurb(sk->idle_outurb->number_of_packets, sk->idle_inurb);
+	err = usb_submit_urb(sk->idle_inurb, GFP_ATOMIC);
+	if (err < 0) {
+		snd_printk(KERN_ERR "%i\n", err);
+		return err;
+	}
+	sk->idle_inurb = sk->completed_inurb;
+	sk->completed_inurb = inurb;
+	err = usb_submit_urb(sk->idle_outurb, GFP_ATOMIC);
+	if (err < 0) {
+		snd_printk(KERN_ERR "%i\n", err);
+		return err;
+	}
+	sk->idle_outurb = sk->completed_outurb;
+	sk->completed_outurb = outurb;
+	return 0;
+}
+
+#ifdef DEBUG_LOOP_BACK
+/*
+  This loop_back() shows how to read/write the period data.
+ */
+static void loop_back(struct usb_stream *s)
+{
+	char *i, *o;
+	int il, ol, l, p;
+	struct urb *iu;
+	struct usb_iso_packet_descriptor *id;
+
+	o = s->playback1st_to;
+	ol = s->playback1st_size;
+	l = 0;
+
+	if (s->insplit_pack >= 0) {
+		iu = sk->idle_inurb;
+		id = iu->iso_frame_desc;
+		p = s->insplit_pack;
+	} else
+		goto second;
+loop:
+	for (; p < iu->number_of_packets && l < s->period_size; ++p) {
+		i = iu->transfer_buffer + id[p].offset;
+		il = id[p].actual_length;
+		if (l + il > s->period_size)
+			il = s->period_size - l;
+		if (il <= ol) {
+			memcpy(o, i, il);
+			o += il;
+			ol -= il;
+		} else {
+			memcpy(o, i, ol);
+			singen_6pack(o, ol);
+			o = s->playback_to;
+			memcpy(o, i + ol, il - ol);
+			o += il - ol;
+			ol = s->period_size - s->playback1st_size;
+		}
+		l += il;
+	}
+	if (iu == sk->completed_inurb) {
+		if (l != s->period_size)
+			printk(KERN_DEBUG"%s:%i %i\n", __func__, __LINE__,
+			       l/(int)s->cfg.frame_size);
+
+		return;
+	}
+second:
+	iu = sk->completed_inurb;
+	id = iu->iso_frame_desc;
+	p = 0;
+	goto loop;
+
+}
+#else
+static void loop_back(struct usb_stream *s)
+{
+}
+#endif
+
+static void stream_idle(struct usb_stream_kernel *sk,
+			struct urb *inurb, struct urb *outurb)
+{
+	struct usb_stream *s = sk->s;
+	int l, p;
+	int insize = s->idle_insize;
+	int urb_size = 0;
+
+	s->inpacket_split = s->next_inpacket_split;
+	s->inpacket_split_at = s->next_inpacket_split_at;
+	s->next_inpacket_split = -1;
+	s->next_inpacket_split_at = 0;
+
+	for (p = 0; p < inurb->number_of_packets; ++p) {
+		struct usb_iso_packet_descriptor *id = inurb->iso_frame_desc;
+		l = id[p].actual_length;
+		if (unlikely(l == 0 || id[p].status)) {
+			snd_printk(KERN_WARNING "underrun, status=%u\n",
+				   id[p].status);
+			goto err_out;
+		}
+		s->inpacket_head++;
+		s->inpacket_head %= s->inpackets;
+		if (s->inpacket_split == -1)
+			s->inpacket_split = s->inpacket_head;
+
+		s->inpacket[s->inpacket_head].offset =
+			id[p].offset + (inurb->transfer_buffer - (void *)s);
+		s->inpacket[s->inpacket_head].length = l;
+		if (insize + l > s->period_size &&
+		    s->next_inpacket_split == -1) {
+			s->next_inpacket_split = s->inpacket_head;
+			s->next_inpacket_split_at = s->period_size - insize;
+		}
+		insize += l;
+		urb_size += l;
+	}
+	s->idle_insize += urb_size - s->period_size;
+	if (s->idle_insize < 0) {
+		snd_printk(KERN_WARNING "%i\n",
+			   (s->idle_insize)/(int)s->cfg.frame_size);
+		goto err_out;
+	}
+	s->insize_done += urb_size;
+
+	l = s->idle_outsize;
+	s->outpacket[0].offset = (sk->idle_outurb->transfer_buffer -
+				  sk->write_page) - l;
+
+	if (usb_stream_prepare_playback(sk, inurb) < 0)
+		goto err_out;
+
+	s->outpacket[0].length = sk->idle_outurb->transfer_buffer_length + l;
+	s->outpacket[1].offset = sk->completed_outurb->transfer_buffer -
+		sk->write_page;
+
+	if (submit_urbs(sk, inurb, outurb) < 0)
+		goto err_out;
+
+	loop_back(s);
+	s->periods_done++;
+	wake_up_all(&sk->sleep);
+	return;
+err_out:
+	s->state = usb_stream_xrun;
+	wake_up_all(&sk->sleep);
+}
+
+static void i_capture_idle(struct urb *urb)
+{
+	struct usb_stream_kernel *sk = urb->context;
+	if (balance_capture(sk, urb))
+		stream_idle(sk, urb, sk->i_urb);
+}
+
+static void i_playback_idle(struct urb *urb)
+{
+	struct usb_stream_kernel *sk = urb->context;
+	if (balance_playback(sk, urb))
+		stream_idle(sk, sk->i_urb, urb);
+}
+
+static void stream_start(struct usb_stream_kernel *sk,
+			 struct urb *inurb, struct urb *outurb)
+{
+	struct usb_stream *s = sk->s;
+	if (s->state >= usb_stream_sync1) {
+		int l, p, max_diff, max_diff_0;
+		int urb_size = 0;
+		unsigned frames_per_packet, min_frames = 0;
+		frames_per_packet = (s->period_size - s->idle_insize);
+		frames_per_packet <<= 8;
+		frames_per_packet /=
+			s->cfg.frame_size * inurb->number_of_packets;
+		frames_per_packet++;
+
+		max_diff_0 = s->cfg.frame_size;
+		if (s->cfg.period_frames >= 256)
+			max_diff_0 <<= 1;
+		if (s->cfg.period_frames >= 1024)
+			max_diff_0 <<= 1;
+		max_diff = max_diff_0;
+		for (p = 0; p < inurb->number_of_packets; ++p) {
+			int diff;
+			l = inurb->iso_frame_desc[p].actual_length;
+			urb_size += l;
+
+			min_frames += frames_per_packet;
+			diff = urb_size -
+				(min_frames >> 8) * s->cfg.frame_size;
+			if (diff < max_diff) {
+				snd_printdd(KERN_DEBUG "%i %i %i %i\n",
+					    s->insize_done,
+					    urb_size / (int)s->cfg.frame_size,
+					    inurb->number_of_packets, diff);
+				max_diff = diff;
+			}
+		}
+		s->idle_insize -= max_diff - max_diff_0;
+		s->idle_insize += urb_size - s->period_size;
+		if (s->idle_insize < 0) {
+			snd_printk("%i %i %i\n",
+				   s->idle_insize, urb_size, s->period_size);
+			return;
+		} else if (s->idle_insize == 0) {
+			s->next_inpacket_split =
+				(s->inpacket_head + 1) % s->inpackets;
+			s->next_inpacket_split_at = 0;
+		} else {
+			unsigned split = s->inpacket_head;
+			l = s->idle_insize;
+			while (l > s->inpacket[split].length) {
+				l -= s->inpacket[split].length;
+				if (split == 0)
+					split = s->inpackets - 1;
+				else
+					split--;
+			}
+			s->next_inpacket_split = split;
+			s->next_inpacket_split_at =
+				s->inpacket[split].length - l;
+		}
+
+		s->insize_done += urb_size;
+
+		if (usb_stream_prepare_playback(sk, inurb) < 0)
+			return;
+
+	} else
+		playback_prep_freqn(sk, sk->idle_outurb);
+
+	if (submit_urbs(sk, inurb, outurb) < 0)
+		return;
+
+	if (s->state == usb_stream_sync1 && s->insize_done > 360000) {
+		/* just guesswork                            ^^^^^^ */
+		s->state = usb_stream_ready;
+		subs_set_complete(sk->inurb, i_capture_idle);
+		subs_set_complete(sk->outurb, i_playback_idle);
+	}
+}
+
+static void i_capture_start(struct urb *urb)
+{
+	struct usb_iso_packet_descriptor *id = urb->iso_frame_desc;
+	struct usb_stream_kernel *sk = urb->context;
+	struct usb_stream *s = sk->s;
+	int p;
+	int empty = 0;
+
+	if (urb->status) {
+		snd_printk(KERN_WARNING "status=%i\n", urb->status);
+		return;
+	}
+
+	for (p = 0; p < urb->number_of_packets; ++p) {
+		int l = id[p].actual_length;
+		if (l < s->cfg.frame_size) {
+			++empty;
+			if (s->state >= usb_stream_sync0) {
+				snd_printk(KERN_WARNING "%i\n", l);
+				return;
+			}
+		}
+		s->inpacket_head++;
+		s->inpacket_head %= s->inpackets;
+		s->inpacket[s->inpacket_head].offset =
+			id[p].offset + (urb->transfer_buffer - (void *)s);
+		s->inpacket[s->inpacket_head].length = l;
+	}
+#ifdef SHOW_EMPTY
+	if (empty) {
+		printk(KERN_DEBUG"%s:%i: %i", __func__, __LINE__,
+		       urb->iso_frame_desc[0].actual_length);
+		for (pack = 1; pack < urb->number_of_packets; ++pack) {
+			int l = urb->iso_frame_desc[pack].actual_length;
+			printk(" %i", l);
+		}
+		printk("\n");
+	}
+#endif
+	if (!empty && s->state < usb_stream_sync1)
+		++s->state;
+
+	if (balance_capture(sk, urb))
+		stream_start(sk, urb, sk->i_urb);
+}
+
+static void i_playback_start(struct urb *urb)
+{
+	struct usb_stream_kernel *sk = urb->context;
+	if (balance_playback(sk, urb))
+		stream_start(sk, sk->i_urb, urb);
+}
+
+int usb_stream_start(struct usb_stream_kernel *sk)
+{
+	struct usb_stream *s = sk->s;
+	int frame = 0, iters = 0;
+	int u, err;
+	int try = 0;
+
+	if (s->state != usb_stream_stopped)
+		return -EAGAIN;
+
+	subs_set_complete(sk->inurb, i_capture_start);
+	subs_set_complete(sk->outurb, i_playback_start);
+	memset(sk->write_page, 0, s->write_size);
+dotry:
+	s->insize_done = 0;
+	s->idle_insize = 0;
+	s->idle_outsize = 0;
+	s->sync_packet = -1;
+	s->inpacket_head = -1;
+	sk->iso_frame_balance = 0;
+	++try;
+	for (u = 0; u < 2; u++) {
+		struct urb *inurb = sk->inurb[u];
+		struct urb *outurb = sk->outurb[u];
+		playback_prep_freqn(sk, outurb);
+		inurb->number_of_packets = outurb->number_of_packets;
+		inurb->transfer_buffer_length =
+			inurb->number_of_packets *
+			inurb->iso_frame_desc[0].length;
+		preempt_disable();
+		if (u == 0) {
+			int now;
+			struct usb_device *dev = inurb->dev;
+			frame = usb_get_current_frame_number(dev);
+			do {
+				now = usb_get_current_frame_number(dev);
+				++iters;
+			} while (now > -1 && now == frame);
+		}
+		err = usb_submit_urb(inurb, GFP_ATOMIC);
+		if (err < 0) {
+			preempt_enable();
+			snd_printk(KERN_ERR"usb_submit_urb(sk->inurb[%i])"
+				   " returned %i\n", u, err);
+			return err;
+		}
+		err = usb_submit_urb(outurb, GFP_ATOMIC);
+		if (err < 0) {
+			preempt_enable();
+			snd_printk(KERN_ERR"usb_submit_urb(sk->outurb[%i])"
+				   " returned %i\n", u, err);
+			return err;
+		}
+		preempt_enable();
+		if (inurb->start_frame != outurb->start_frame) {
+			snd_printd(KERN_DEBUG
+				   "u[%i] start_frames differ in:%u out:%u\n",
+				   u, inurb->start_frame, outurb->start_frame);
+			goto check_retry;
+		}
+	}
+	snd_printdd(KERN_DEBUG "%i %i\n", frame, iters);
+	try = 0;
+check_retry:
+	if (try) {
+		usb_stream_stop(sk);
+		if (try < 5) {
+			msleep(1500);
+			snd_printd(KERN_DEBUG "goto dotry;\n");
+			goto dotry;
+		}
+		snd_printk(KERN_WARNING"couldn't start"
+			   " all urbs on the same start_frame.\n");
+		return -EFAULT;
+	}
+
+	sk->idle_inurb = sk->inurb[USB_STREAM_NURBS - 2];
+	sk->idle_outurb = sk->outurb[USB_STREAM_NURBS - 2];
+	sk->completed_inurb = sk->inurb[USB_STREAM_NURBS - 1];
+	sk->completed_outurb = sk->outurb[USB_STREAM_NURBS - 1];
+
+/* wait, check */
+	{
+		int wait_ms = 3000;
+		while (s->state != usb_stream_ready && wait_ms > 0) {
+			snd_printdd(KERN_DEBUG "%i\n", s->state);
+			msleep(200);
+			wait_ms -= 200;
+		}
+	}
+
+	return s->state == usb_stream_ready ? 0 : -EFAULT;
+}
+
+
+/*                             stop                                   */
+
+void usb_stream_stop(struct usb_stream_kernel *sk)
+{
+	int u;
+	if (!sk->s)
+		return;
+	for (u = 0; u < USB_STREAM_NURBS; ++u) {
+		usb_kill_urb(sk->inurb[u]);
+		usb_kill_urb(sk->outurb[u]);
+	}
+	sk->s->state = usb_stream_stopped;
+	msleep(400);
+}