ALSA: snd-usb: move code from urb.c to endpoint.c

No code altered at this point, simply preparing for upcoming
refactorizations.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 948 insertions, 0 deletions

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index b3ee7cf243df..81c6edecd862 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -15,3 +15,951 @@
  *
  */
 
+#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 "endpoint.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_free_coherent(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_free_coherent(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;
+        subs->freqshift = INT_MIN;
+        /* 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_FULL)
+                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_alloc_coherent(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_alloc_coherent(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 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 = min(4u, ctx->subs->syncmaxsize);
+        urb->iso_frame_desc[0].offset = 0;
+        return 0;
+}
+
+/*
+ * process after playback sync complete
+ *
+ * Full speed devices report feedback values in 10.14 format as samples per
+ * frame, high speed devices in 16.16 format as samples per microframe.
+ * Because the Audio Class 1 spec was written before USB 2.0, many high speed
+ * devices use a wrong interpretation, some others use an entirely different
+ * format.  Therefore, we cannot predict what format any particular device uses
+ * and must detect it automatically.
+ */
+static int retire_playback_sync_urb(struct snd_usb_substream *subs,
+                                    struct snd_pcm_runtime *runtime,
+                                    struct urb *urb)
+{
+        unsigned int f;
+        int shift;
+        unsigned long flags;
+
+        if (urb->iso_frame_desc[0].status != 0 ||
+            urb->iso_frame_desc[0].actual_length < 3)
+                return 0;
+
+        f = le32_to_cpup(urb->transfer_buffer);
+        if (urb->iso_frame_desc[0].actual_length == 3)
+                f &= 0x00ffffff;
+        else
+                f &= 0x0fffffff;
+        if (f == 0)
+                return 0;
+
+        if (unlikely(subs->freqshift == INT_MIN)) {
+                /*
+                 * The first time we see a feedback value, determine its format
+                 * by shifting it left or right until it matches the nominal
+                 * frequency value.  This assumes that the feedback does not
+                 * differ from the nominal value more than +50% or -25%.
+                 */
+                shift = 0;
+                while (f < subs->freqn - subs->freqn / 4) {
+                        f <<= 1;
+                        shift++;
+                }
+                while (f > subs->freqn + subs->freqn / 2) {
+                        f >>= 1;
+                        shift--;
+                }
+                subs->freqshift = shift;
+        }
+        else if (subs->freqshift >= 0)
+                f <<= subs->freqshift;
+        else
+                f >>= -subs->freqshift;
+
+        if (likely(f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax)) {
+                /*
+                 * If the frequency looks valid, set it.
+                 * This value is referred to in prepare_playback_urb().
+                 */
+                spin_lock_irqsave(&subs->lock, flags);
+                subs->freqm = f;
+                spin_unlock_irqrestore(&subs->lock, flags);
+        } else {
+                /*
+                 * Out of range; maybe the shift value is wrong.
+                 * Reset it so that we autodetect again the next time.
+                 */
+                subs->freqshift = INT_MIN;
+        }
+
+        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;
+
+        /* update delay with exact number of samples queued */
+        runtime->delay = subs->last_delay;
+        runtime->delay += frames;
+        subs->last_delay = runtime->delay;
+
+        /* realign last_frame_number */
+        subs->last_frame_number = usb_get_current_frame_number(subs->dev);
+        subs->last_frame_number &= 0xFF; /* keep 8 LSBs */
+
+        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;
+        int est_delay;
+
+        spin_lock_irqsave(&subs->lock, flags);
+
+        est_delay = snd_usb_pcm_delay(subs, runtime->rate);
+        /* update delay with exact number of samples played */
+        if (processed > subs->last_delay)
+                subs->last_delay = 0;
+        else
+                subs->last_delay -= processed;
+        runtime->delay = subs->last_delay;
+
+        /*
+         * Report when delay estimate is off by more than 2ms.
+         * The error should be lower than 2ms since the estimate relies
+         * on two reads of a counter updated every ms.
+         */
+        if (abs(est_delay - subs->last_delay) * 1000 > runtime->rate * 2)
+                snd_printk(KERN_DEBUG "delay: estimated %d, actual %d\n",
+                        est_delay, subs->last_delay);
+
+        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,
+        },
+};
+
+/*
+ * 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;
+        subs->ops = audio_urb_ops[stream];
+        if (snd_usb_get_speed(subs->dev) >= USB_SPEED_HIGH)
+                subs->ops.prepare_sync = prepare_capture_sync_urb_hs;
+
+        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;
+}
+