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urb.c

/*
 *   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/usb.h>
#include <linux/usb/audio.h>

#include <sound/core.h>
#include <sound/pcm.h>

#include "usbaudio.h"
#include "helper.h"
#include "card.h"
#include "urb.h"
#include "pcm.h"

/*
 * 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 int 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 int rate)
{
      return ((rate << 10) + 62) / 125;
}

/*
 * unlink active urbs.
 */
static int deactivate_urbs(struct snd_usb_substream *subs, int force, int can_sleep)
{
      struct snd_usb_audio *chip = subs->stream->chip;
      unsigned int i;
      int async;

      subs->running = 0;

      if (!force && subs->stream->chip->shutdown) /* to be sure... */
            return -EBADFD;

      async = !can_sleep && chip->async_unlink;

      if (!async && in_interrupt())
            return 0;

      for (i = 0; i < subs->nurbs; i++) {
            if (test_bit(i, &subs->active_mask)) {
                  if (!test_and_set_bit(i, &subs->unlink_mask)) {
                        struct urb *u = subs->dataurb[i].urb;
                        if (async)
                              usb_unlink_urb(u);
                        else
                              usb_kill_urb(u);
                  }
            }
      }
      if (subs->syncpipe) {
            for (i = 0; i < SYNC_URBS; i++) {
                  if (test_bit(i+16, &subs->active_mask)) {
                        if (!test_and_set_bit(i+16, &subs->unlink_mask)) {
                              struct urb *u = subs->syncurb[i].urb;
                              if (async)
                                    usb_unlink_urb(u);
                              else
                                    usb_kill_urb(u);
                        }
                  }
            }
      }
      return 0;
}


/*
 * release a urb data
 */
static void release_urb_ctx(struct snd_urb_ctx *u)
{
      if (u->urb) {
            if (u->buffer_size)
                  usb_buffer_free(u->subs->dev, u->buffer_size,
                              u->urb->transfer_buffer,
                              u->urb->transfer_dma);
            usb_free_urb(u->urb);
            u->urb = NULL;
      }
}

/*
 *  wait until all urbs are processed.
 */
static int wait_clear_urbs(struct snd_usb_substream *subs)
{
      unsigned long end_time = jiffies + msecs_to_jiffies(1000);
      unsigned int i;
      int alive;

      do {
            alive = 0;
            for (i = 0; i < subs->nurbs; i++) {
                  if (test_bit(i, &subs->active_mask))
                        alive++;
            }
            if (subs->syncpipe) {
                  for (i = 0; i < SYNC_URBS; i++) {
                        if (test_bit(i + 16, &subs->active_mask))
                              alive++;
                  }
            }
            if (! alive)
                  break;
            schedule_timeout_uninterruptible(1);
      } while (time_before(jiffies, end_time));
      if (alive)
            snd_printk(KERN_ERR "timeout: still %d active urbs..\n", alive);
      return 0;
}

/*
 * release a substream
 */
void snd_usb_release_substream_urbs(struct snd_usb_substream *subs, int force)
{
      int i;

      /* stop urbs (to be sure) */
      deactivate_urbs(subs, force, 1);
      wait_clear_urbs(subs);

      for (i = 0; i < MAX_URBS; i++)
            release_urb_ctx(&subs->dataurb[i]);
      for (i = 0; i < SYNC_URBS; i++)
            release_urb_ctx(&subs->syncurb[i]);
      usb_buffer_free(subs->dev, SYNC_URBS * 4,
                  subs->syncbuf, subs->sync_dma);
      subs->syncbuf = NULL;
      subs->nurbs = 0;
}

/*
 * complete callback from data urb
 */
static void snd_complete_urb(struct urb *urb)
{
      struct snd_urb_ctx *ctx = urb->context;
      struct snd_usb_substream *subs = ctx->subs;
      struct snd_pcm_substream *substream = ctx->subs->pcm_substream;
      int err = 0;

      if ((subs->running && subs->ops.retire(subs, substream->runtime, urb)) ||
          !subs->running || /* can be stopped during retire callback */
          (err = subs->ops.prepare(subs, substream->runtime, urb)) < 0 ||
          (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
            clear_bit(ctx->index, &subs->active_mask);
            if (err < 0) {
                  snd_printd(KERN_ERR "cannot submit urb (err = %d)\n", err);
                  snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
            }
      }
}


/*
 * complete callback from sync urb
 */
static void snd_complete_sync_urb(struct urb *urb)
{
      struct snd_urb_ctx *ctx = urb->context;
      struct snd_usb_substream *subs = ctx->subs;
      struct snd_pcm_substream *substream = ctx->subs->pcm_substream;
      int err = 0;

      if ((subs->running && subs->ops.retire_sync(subs, substream->runtime, urb)) ||
          !subs->running || /* can be stopped during retire callback */
          (err = subs->ops.prepare_sync(subs, substream->runtime, urb)) < 0 ||
          (err = usb_submit_urb(urb, GFP_ATOMIC)) < 0) {
            clear_bit(ctx->index + 16, &subs->active_mask);
            if (err < 0) {
                  snd_printd(KERN_ERR "cannot submit sync urb (err = %d)\n", err);
                  snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
            }
      }
}


/*
 * initialize a substream for plaback/capture
 */
int snd_usb_init_substream_urbs(struct snd_usb_substream *subs,
                        unsigned int period_bytes,
                        unsigned int rate,
                        unsigned int frame_bits)
{
      unsigned int maxsize, i;
      int is_playback = subs->direction == SNDRV_PCM_STREAM_PLAYBACK;
      unsigned int urb_packs, total_packs, packs_per_ms;
      struct snd_usb_audio *chip = subs->stream->chip;

      /* calculate the frequency in 16.16 format */
      if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
            subs->freqn = get_usb_full_speed_rate(rate);
      else
            subs->freqn = get_usb_high_speed_rate(rate);
      subs->freqm = subs->freqn;
      /* calculate max. frequency */
      if (subs->maxpacksize) {
            /* whatever fits into a max. size packet */
            maxsize = subs->maxpacksize;
            subs->freqmax = (maxsize / (frame_bits >> 3))
                        << (16 - subs->datainterval);
      } else {
            /* no max. packet size: just take 25% higher than nominal */
            subs->freqmax = subs->freqn + (subs->freqn >> 2);
            maxsize = ((subs->freqmax + 0xffff) * (frame_bits >> 3))
                        >> (16 - subs->datainterval);
      }
      subs->phase = 0;

      if (subs->fill_max)
            subs->curpacksize = subs->maxpacksize;
      else
            subs->curpacksize = maxsize;

      if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH)
            packs_per_ms = 8 >> subs->datainterval;
      else
            packs_per_ms = 1;

      if (is_playback) {
            urb_packs = max(chip->nrpacks, 1);
            urb_packs = min(urb_packs, (unsigned int)MAX_PACKS);
      } else
            urb_packs = 1;
      urb_packs *= packs_per_ms;
      if (subs->syncpipe)
            urb_packs = min(urb_packs, 1U << subs->syncinterval);

      /* decide how many packets to be used */
      if (is_playback) {
            unsigned int minsize, maxpacks;
            /* determine how small a packet can be */
            minsize = (subs->freqn >> (16 - subs->datainterval))
                    * (frame_bits >> 3);
            /* with sync from device, assume it can be 12% lower */
            if (subs->syncpipe)
                  minsize -= minsize >> 3;
            minsize = max(minsize, 1u);
            total_packs = (period_bytes + minsize - 1) / minsize;
            /* we need at least two URBs for queueing */
            if (total_packs < 2) {
                  total_packs = 2;
            } else {
                  /* and we don't want too long a queue either */
                  maxpacks = max(MAX_QUEUE * packs_per_ms, urb_packs * 2);
                  total_packs = min(total_packs, maxpacks);
            }
      } else {
            while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
                  urb_packs >>= 1;
            total_packs = MAX_URBS * urb_packs;
      }
      subs->nurbs = (total_packs + urb_packs - 1) / urb_packs;
      if (subs->nurbs > MAX_URBS) {
            /* too much... */
            subs->nurbs = MAX_URBS;
            total_packs = MAX_URBS * urb_packs;
      } else if (subs->nurbs < 2) {
            /* too little - we need at least two packets
             * to ensure contiguous playback/capture
             */
            subs->nurbs = 2;
      }

      /* allocate and initialize data urbs */
      for (i = 0; i < subs->nurbs; i++) {
            struct snd_urb_ctx *u = &subs->dataurb[i];
            u->index = i;
            u->subs = subs;
            u->packets = (i + 1) * total_packs / subs->nurbs
                  - i * total_packs / subs->nurbs;
            u->buffer_size = maxsize * u->packets;
            if (subs->fmt_type == UAC_FORMAT_TYPE_II)
                  u->packets++; /* for transfer delimiter */
            u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
            if (!u->urb)
                  goto out_of_memory;
            u->urb->transfer_buffer =
                  usb_buffer_alloc(subs->dev, u->buffer_size, GFP_KERNEL,
                               &u->urb->transfer_dma);
            if (!u->urb->transfer_buffer)
                  goto out_of_memory;
            u->urb->pipe = subs->datapipe;
            u->urb->transfer_flags = URB_ISO_ASAP | URB_NO_TRANSFER_DMA_MAP;
            u->urb->interval = 1 << subs->datainterval;
            u->urb->context = u;
            u->urb->complete = snd_complete_urb;
      }

      if (subs->syncpipe) {
            /* allocate and initialize sync urbs */
            subs->syncbuf = usb_buffer_alloc(subs->dev, SYNC_URBS * 4,
                                     GFP_KERNEL, &subs->sync_dma);
            if (!subs->syncbuf)
                  goto out_of_memory;
            for (i = 0; i < SYNC_URBS; i++) {
                  struct snd_urb_ctx *u = &subs->syncurb[i];
                  u->index = i;
                  u->subs = subs;
                  u->packets = 1;
                  u->urb = usb_alloc_urb(1, GFP_KERNEL);
                  if (!u->urb)
                        goto out_of_memory;
                  u->urb->transfer_buffer = subs->syncbuf + i * 4;
                  u->urb->transfer_dma = subs->sync_dma + i * 4;
                  u->urb->transfer_buffer_length = 4;
                  u->urb->pipe = subs->syncpipe;
                  u->urb->transfer_flags = URB_ISO_ASAP |
                                     URB_NO_TRANSFER_DMA_MAP;
                  u->urb->number_of_packets = 1;
                  u->urb->interval = 1 << subs->syncinterval;
                  u->urb->context = u;
                  u->urb->complete = snd_complete_sync_urb;
            }
      }
      return 0;

out_of_memory:
      snd_usb_release_substream_urbs(subs, 0);
      return -ENOMEM;
}

/*
 * prepare urb for full speed capture sync pipe
 *
 * fill the length and offset of each urb descriptor.
 * the fixed 10.14 frequency is passed through the pipe.
 */
static int prepare_capture_sync_urb(struct snd_usb_substream *subs,
                            struct snd_pcm_runtime *runtime,
                            struct urb *urb)
{
      unsigned char *cp = urb->transfer_buffer;
      struct snd_urb_ctx *ctx = urb->context;

      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      urb->iso_frame_desc[0].length = 3;
      urb->iso_frame_desc[0].offset = 0;
      cp[0] = subs->freqn >> 2;
      cp[1] = subs->freqn >> 10;
      cp[2] = subs->freqn >> 18;
      return 0;
}

/*
 * prepare urb for high speed capture sync pipe
 *
 * fill the length and offset of each urb descriptor.
 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
 */
static int prepare_capture_sync_urb_hs(struct snd_usb_substream *subs,
                               struct snd_pcm_runtime *runtime,
                               struct urb *urb)
{
      unsigned char *cp = urb->transfer_buffer;
      struct snd_urb_ctx *ctx = urb->context;

      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      urb->iso_frame_desc[0].length = 4;
      urb->iso_frame_desc[0].offset = 0;
      cp[0] = subs->freqn;
      cp[1] = subs->freqn >> 8;
      cp[2] = subs->freqn >> 16;
      cp[3] = subs->freqn >> 24;
      return 0;
}

/*
 * process after capture sync complete
 * - nothing to do
 */
static int retire_capture_sync_urb(struct snd_usb_substream *subs,
                           struct snd_pcm_runtime *runtime,
                           struct urb *urb)
{
      return 0;
}

/*
 * prepare urb for capture data pipe
 *
 * fill the offset and length of each descriptor.
 *
 * we use a temporary buffer to write the captured data.
 * since the length of written data is determined by host, we cannot
 * write onto the pcm buffer directly...  the data is thus copied
 * later at complete callback to the global buffer.
 */
static int prepare_capture_urb(struct snd_usb_substream *subs,
                         struct snd_pcm_runtime *runtime,
                         struct urb *urb)
{
      int i, offs;
      struct snd_urb_ctx *ctx = urb->context;

      offs = 0;
      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      for (i = 0; i < ctx->packets; i++) {
            urb->iso_frame_desc[i].offset = offs;
            urb->iso_frame_desc[i].length = subs->curpacksize;
            offs += subs->curpacksize;
      }
      urb->transfer_buffer_length = offs;
      urb->number_of_packets = ctx->packets;
      return 0;
}

/*
 * process after capture complete
 *
 * copy the data from each desctiptor to the pcm buffer, and
 * update the current position.
 */
static int retire_capture_urb(struct snd_usb_substream *subs,
                        struct snd_pcm_runtime *runtime,
                        struct urb *urb)
{
      unsigned long flags;
      unsigned char *cp;
      int i;
      unsigned int stride, frames, bytes, oldptr;
      int period_elapsed = 0;

      stride = runtime->frame_bits >> 3;

      for (i = 0; i < urb->number_of_packets; i++) {
            cp = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset;
            if (urb->iso_frame_desc[i].status) {
                  snd_printd(KERN_ERR "frame %d active: %d\n", i, urb->iso_frame_desc[i].status);
                  // continue;
            }
            bytes = urb->iso_frame_desc[i].actual_length;
            frames = bytes / stride;
            if (!subs->txfr_quirk)
                  bytes = frames * stride;
            if (bytes % (runtime->sample_bits >> 3) != 0) {
#ifdef CONFIG_SND_DEBUG_VERBOSE
                  int oldbytes = bytes;
#endif
                  bytes = frames * stride;
                  snd_printdd(KERN_ERR "Corrected urb data len. %d->%d\n",
                                          oldbytes, bytes);
            }
            /* update the current pointer */
            spin_lock_irqsave(&subs->lock, flags);
            oldptr = subs->hwptr_done;
            subs->hwptr_done += bytes;
            if (subs->hwptr_done >= runtime->buffer_size * stride)
                  subs->hwptr_done -= runtime->buffer_size * stride;
            frames = (bytes + (oldptr % stride)) / stride;
            subs->transfer_done += frames;
            if (subs->transfer_done >= runtime->period_size) {
                  subs->transfer_done -= runtime->period_size;
                  period_elapsed = 1;
            }
            spin_unlock_irqrestore(&subs->lock, flags);
            /* copy a data chunk */
            if (oldptr + bytes > runtime->buffer_size * stride) {
                  unsigned int bytes1 =
                              runtime->buffer_size * stride - oldptr;
                  memcpy(runtime->dma_area + oldptr, cp, bytes1);
                  memcpy(runtime->dma_area, cp + bytes1, bytes - bytes1);
            } else {
                  memcpy(runtime->dma_area + oldptr, cp, bytes);
            }
      }
      if (period_elapsed)
            snd_pcm_period_elapsed(subs->pcm_substream);
      return 0;
}

/*
 * Process after capture complete when paused.  Nothing to do.
 */
static int retire_paused_capture_urb(struct snd_usb_substream *subs,
                             struct snd_pcm_runtime *runtime,
                             struct urb *urb)
{
      return 0;
}


/*
 * prepare urb for full speed playback sync pipe
 *
 * set up the offset and length to receive the current frequency.
 */

static int prepare_playback_sync_urb(struct snd_usb_substream *subs,
                             struct snd_pcm_runtime *runtime,
                             struct urb *urb)
{
      struct snd_urb_ctx *ctx = urb->context;

      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      urb->iso_frame_desc[0].length = 3;
      urb->iso_frame_desc[0].offset = 0;
      return 0;
}

/*
 * prepare urb for high speed playback sync pipe
 *
 * set up the offset and length to receive the current frequency.
 */

static int prepare_playback_sync_urb_hs(struct snd_usb_substream *subs,
                              struct snd_pcm_runtime *runtime,
                              struct urb *urb)
{
      struct snd_urb_ctx *ctx = urb->context;

      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      urb->iso_frame_desc[0].length = 4;
      urb->iso_frame_desc[0].offset = 0;
      return 0;
}

/*
 * process after full speed playback sync complete
 *
 * retrieve the current 10.14 frequency from pipe, and set it.
 * the value is referred in prepare_playback_urb().
 */
static int retire_playback_sync_urb(struct snd_usb_substream *subs,
                            struct snd_pcm_runtime *runtime,
                            struct urb *urb)
{
      unsigned int f;
      unsigned long flags;

      if (urb->iso_frame_desc[0].status == 0 &&
          urb->iso_frame_desc[0].actual_length == 3) {
            f = combine_triple((u8*)urb->transfer_buffer) << 2;
            if (f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax) {
                  spin_lock_irqsave(&subs->lock, flags);
                  subs->freqm = f;
                  spin_unlock_irqrestore(&subs->lock, flags);
            }
      }

      return 0;
}

/*
 * process after high speed playback sync complete
 *
 * retrieve the current 12.13 frequency from pipe, and set it.
 * the value is referred in prepare_playback_urb().
 */
static int retire_playback_sync_urb_hs(struct snd_usb_substream *subs,
                               struct snd_pcm_runtime *runtime,
                               struct urb *urb)
{
      unsigned int f;
      unsigned long flags;

      if (urb->iso_frame_desc[0].status == 0 &&
          urb->iso_frame_desc[0].actual_length == 4) {
            f = combine_quad((u8*)urb->transfer_buffer) & 0x0fffffff;
            if (f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax) {
                  spin_lock_irqsave(&subs->lock, flags);
                  subs->freqm = f;
                  spin_unlock_irqrestore(&subs->lock, flags);
            }
      }

      return 0;
}

/*
 * process after E-Mu 0202/0404/Tracker Pre high speed playback sync complete
 *
 * These devices return the number of samples per packet instead of the number
 * of samples per microframe.
 */
static int retire_playback_sync_urb_hs_emu(struct snd_usb_substream *subs,
                                 struct snd_pcm_runtime *runtime,
                                 struct urb *urb)
{
      unsigned int f;
      unsigned long flags;

      if (urb->iso_frame_desc[0].status == 0 &&
          urb->iso_frame_desc[0].actual_length == 4) {
            f = combine_quad((u8*)urb->transfer_buffer) & 0x0fffffff;
            f >>= subs->datainterval;
            if (f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax) {
                  spin_lock_irqsave(&subs->lock, flags);
                  subs->freqm = f;
                  spin_unlock_irqrestore(&subs->lock, flags);
            }
      }

      return 0;
}

/* determine the number of frames in the next packet */
static int snd_usb_audio_next_packet_size(struct snd_usb_substream *subs)
{
      if (subs->fill_max)
            return subs->maxframesize;
      else {
            subs->phase = (subs->phase & 0xffff)
                  + (subs->freqm << subs->datainterval);
            return min(subs->phase >> 16, subs->maxframesize);
      }
}

/*
 * Prepare urb for streaming before playback starts or when paused.
 *
 * We don't have any data, so we send silence.
 */
static int prepare_nodata_playback_urb(struct snd_usb_substream *subs,
                               struct snd_pcm_runtime *runtime,
                               struct urb *urb)
{
      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;
      for (i = 0; i < ctx->packets; ++i) {
            counts = snd_usb_audio_next_packet_size(subs);
            urb->iso_frame_desc[i].offset = offs * stride;
            urb->iso_frame_desc[i].length = counts * stride;
            offs += counts;
      }
      urb->number_of_packets = ctx->packets;
      urb->transfer_buffer_length = offs * stride;
      memset(urb->transfer_buffer,
             runtime->format == SNDRV_PCM_FORMAT_U8 ? 0x80 : 0,
             offs * stride);
      return 0;
}

/*
 * prepare urb for playback data pipe
 *
 * Since a URB can handle only a single linear buffer, we must use double
 * buffering when the data to be transferred overflows the buffer boundary.
 * To avoid inconsistencies when updating hwptr_done, we use double buffering
 * for all URBs.
 */
static int prepare_playback_urb(struct snd_usb_substream *subs,
                        struct snd_pcm_runtime *runtime,
                        struct urb *urb)
{
      int i, stride;
      unsigned int counts, frames, bytes;
      unsigned long flags;
      int period_elapsed = 0;
      struct snd_urb_ctx *ctx = urb->context;

      stride = runtime->frame_bits >> 3;

      frames = 0;
      urb->dev = ctx->subs->dev; /* we need to set this at each time */
      urb->number_of_packets = 0;
      spin_lock_irqsave(&subs->lock, flags);
      for (i = 0; i < ctx->packets; i++) {
            counts = snd_usb_audio_next_packet_size(subs);
            /* set up descriptor */
            urb->iso_frame_desc[i].offset = frames * stride;
            urb->iso_frame_desc[i].length = counts * stride;
            frames += counts;
            urb->number_of_packets++;
            subs->transfer_done += counts;
            if (subs->transfer_done >= runtime->period_size) {
                  subs->transfer_done -= runtime->period_size;
                  period_elapsed = 1;
                  if (subs->fmt_type == UAC_FORMAT_TYPE_II) {
                        if (subs->transfer_done > 0) {
                              /* FIXME: fill-max mode is not
                               * supported yet */
                              frames -= subs->transfer_done;
                              counts -= subs->transfer_done;
                              urb->iso_frame_desc[i].length =
                                    counts * stride;
                              subs->transfer_done = 0;
                        }
                        i++;
                        if (i < ctx->packets) {
                              /* add a transfer delimiter */
                              urb->iso_frame_desc[i].offset =
                                    frames * stride;
                              urb->iso_frame_desc[i].length = 0;
                              urb->number_of_packets++;
                        }
                        break;
                  }
            }
            if (period_elapsed) /* finish at the period boundary */
                  break;
      }
      bytes = frames * stride;
      if (subs->hwptr_done + bytes > runtime->buffer_size * stride) {
            /* err, the transferred area goes over buffer boundary. */
            unsigned int bytes1 =
                  runtime->buffer_size * stride - subs->hwptr_done;
            memcpy(urb->transfer_buffer,
                   runtime->dma_area + subs->hwptr_done, bytes1);
            memcpy(urb->transfer_buffer + bytes1,
                   runtime->dma_area, bytes - bytes1);
      } else {
            memcpy(urb->transfer_buffer,
                   runtime->dma_area + subs->hwptr_done, bytes);
      }
      subs->hwptr_done += bytes;
      if (subs->hwptr_done >= runtime->buffer_size * stride)
            subs->hwptr_done -= runtime->buffer_size * stride;
      runtime->delay += frames;
      spin_unlock_irqrestore(&subs->lock, flags);
      urb->transfer_buffer_length = bytes;
      if (period_elapsed)
            snd_pcm_period_elapsed(subs->pcm_substream);
      return 0;
}

/*
 * process after playback data complete
 * - decrease the delay count again
 */
static int retire_playback_urb(struct snd_usb_substream *subs,
                         struct snd_pcm_runtime *runtime,
                         struct urb *urb)
{
      unsigned long flags;
      int stride = runtime->frame_bits >> 3;
      int processed = urb->transfer_buffer_length / stride;

      spin_lock_irqsave(&subs->lock, flags);
      if (processed > runtime->delay)
            runtime->delay = 0;
      else
            runtime->delay -= processed;
      spin_unlock_irqrestore(&subs->lock, flags);
      return 0;
}

static const char *usb_error_string(int err)
{
      switch (err) {
      case -ENODEV:
            return "no device";
      case -ENOENT:
            return "endpoint not enabled";
      case -EPIPE:
            return "endpoint stalled";
      case -ENOSPC:
            return "not enough bandwidth";
      case -ESHUTDOWN:
            return "device disabled";
      case -EHOSTUNREACH:
            return "device suspended";
      case -EINVAL:
      case -EAGAIN:
      case -EFBIG:
      case -EMSGSIZE:
            return "internal error";
      default:
            return "unknown error";
      }
}

/*
 * set up and start data/sync urbs
 */
static int start_urbs(struct snd_usb_substream *subs, struct snd_pcm_runtime *runtime)
{
      unsigned int i;
      int err;

      if (subs->stream->chip->shutdown)
            return -EBADFD;

      for (i = 0; i < subs->nurbs; i++) {
            if (snd_BUG_ON(!subs->dataurb[i].urb))
                  return -EINVAL;
            if (subs->ops.prepare(subs, runtime, subs->dataurb[i].urb) < 0) {
                  snd_printk(KERN_ERR "cannot prepare datapipe for urb %d\n", i);
                  goto __error;
            }
      }
      if (subs->syncpipe) {
            for (i = 0; i < SYNC_URBS; i++) {
                  if (snd_BUG_ON(!subs->syncurb[i].urb))
                        return -EINVAL;
                  if (subs->ops.prepare_sync(subs, runtime, subs->syncurb[i].urb) < 0) {
                        snd_printk(KERN_ERR "cannot prepare syncpipe for urb %d\n", i);
                        goto __error;
                  }
            }
      }

      subs->active_mask = 0;
      subs->unlink_mask = 0;
      subs->running = 1;
      for (i = 0; i < subs->nurbs; i++) {
            err = usb_submit_urb(subs->dataurb[i].urb, GFP_ATOMIC);
            if (err < 0) {
                  snd_printk(KERN_ERR "cannot submit datapipe "
                           "for urb %d, error %d: %s\n",
                           i, err, usb_error_string(err));
                  goto __error;
            }
            set_bit(i, &subs->active_mask);
      }
      if (subs->syncpipe) {
            for (i = 0; i < SYNC_URBS; i++) {
                  err = usb_submit_urb(subs->syncurb[i].urb, GFP_ATOMIC);
                  if (err < 0) {
                        snd_printk(KERN_ERR "cannot submit syncpipe "
                                 "for urb %d, error %d: %s\n",
                                 i, err, usb_error_string(err));
                        goto __error;
                  }
                  set_bit(i + 16, &subs->active_mask);
            }
      }
      return 0;

 __error:
      // snd_pcm_stop(subs->pcm_substream, SNDRV_PCM_STATE_XRUN);
      deactivate_urbs(subs, 0, 0);
      return -EPIPE;
}


/*
 */
static struct snd_urb_ops audio_urb_ops[2] = {
      {
            .prepare =  prepare_nodata_playback_urb,
            .retire =   retire_playback_urb,
            .prepare_sync =   prepare_playback_sync_urb,
            .retire_sync =    retire_playback_sync_urb,
      },
      {
            .prepare =  prepare_capture_urb,
            .retire =   retire_capture_urb,
            .prepare_sync =   prepare_capture_sync_urb,
            .retire_sync =    retire_capture_sync_urb,
      },
};

static struct snd_urb_ops audio_urb_ops_high_speed[2] = {
      {
            .prepare =  prepare_nodata_playback_urb,
            .retire =   retire_playback_urb,
            .prepare_sync =   prepare_playback_sync_urb_hs,
            .retire_sync =    retire_playback_sync_urb_hs,
      },
      {
            .prepare =  prepare_capture_urb,
            .retire =   retire_capture_urb,
            .prepare_sync =   prepare_capture_sync_urb_hs,
            .retire_sync =    retire_capture_sync_urb,
      },
};

/*
 * initialize the substream instance.
 */

void snd_usb_init_substream(struct snd_usb_stream *as,
                      int stream, struct audioformat *fp)
{
      struct snd_usb_substream *subs = &as->substream[stream];

      INIT_LIST_HEAD(&subs->fmt_list);
      spin_lock_init(&subs->lock);

      subs->stream = as;
      subs->direction = stream;
      subs->dev = as->chip->dev;
      subs->txfr_quirk = as->chip->txfr_quirk;
      if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL) {
            subs->ops = audio_urb_ops[stream];
      } else {
            subs->ops = audio_urb_ops_high_speed[stream];
            switch (as->chip->usb_id) {
            case USB_ID(0x041e, 0x3f02): /* E-Mu 0202 USB */
            case USB_ID(0x041e, 0x3f04): /* E-Mu 0404 USB */
            case USB_ID(0x041e, 0x3f0a): /* E-Mu Tracker Pre */
                  subs->ops.retire_sync = retire_playback_sync_urb_hs_emu;
                  break;
            case USB_ID(0x0763, 0x2080): /* M-Audio Fast Track Ultra 8  */
            case USB_ID(0x0763, 0x2081): /* M-Audio Fast Track Ultra 8R */
                  subs->ops.prepare_sync = prepare_playback_sync_urb;
                  subs->ops.retire_sync = retire_playback_sync_urb;
                  break;
            }
      }

      snd_usb_set_pcm_ops(as->pcm, stream);

      list_add_tail(&fp->list, &subs->fmt_list);
      subs->formats |= fp->formats;
      subs->endpoint = fp->endpoint;
      subs->num_formats++;
      subs->fmt_type = fp->fmt_type;
}

int snd_usb_substream_playback_trigger(struct snd_pcm_substream *substream, int cmd)
{
      struct snd_usb_substream *subs = substream->runtime->private_data;

      switch (cmd) {
      case SNDRV_PCM_TRIGGER_START:
      case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
            subs->ops.prepare = prepare_playback_urb;
            return 0;
      case SNDRV_PCM_TRIGGER_STOP:
            return deactivate_urbs(subs, 0, 0);
      case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
            subs->ops.prepare = prepare_nodata_playback_urb;
            return 0;
      }

      return -EINVAL;
}

int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream, int cmd)
{
      struct snd_usb_substream *subs = substream->runtime->private_data;

      switch (cmd) {
      case SNDRV_PCM_TRIGGER_START:
            subs->ops.retire = retire_capture_urb;
            return start_urbs(subs, substream->runtime);
      case SNDRV_PCM_TRIGGER_STOP:
            return deactivate_urbs(subs, 0, 0);
      case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
            subs->ops.retire = retire_paused_capture_urb;
            return 0;
      case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
            subs->ops.retire = retire_capture_urb;
            return 0;
      }

      return -EINVAL;
}

int snd_usb_substream_prepare(struct snd_usb_substream *subs,
                        struct snd_pcm_runtime *runtime)
{
      /* clear urbs (to be sure) */
      deactivate_urbs(subs, 0, 1);
      wait_clear_urbs(subs);

      /* for playback, submit the URBs now; otherwise, the first hwptr_done
       * updates for all URBs would happen at the same time when starting */
      if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK) {
            subs->ops.prepare = prepare_nodata_playback_urb;
            return start_urbs(subs, runtime);
      }

      return 0;
}


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