Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma

[deliverable/linux.git] / sound / usb / stream.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/init.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/usb/audio.h>
#include <linux/usb/audio-v2.h>

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

#include "usbaudio.h"
#include "card.h"
#include "proc.h"
#include "quirks.h"
#include "endpoint.h"
#include "pcm.h"
#include "helper.h"
#include "format.h"
#include "clock.h"
#include "stream.h"

/*
 * free a substream
 */
static void free_substream(struct snd_usb_substream *subs)
{
        struct audioformat *fp, *n;

        if (!subs->num_formats)
                return; /* not initialized */
        list_for_each_entry_safe(fp, n, &subs->fmt_list, list) {
                kfree(fp->rate_table);
                kfree(fp->chmap);
                kfree(fp);
        }
        kfree(subs->rate_list.list);
}


/*
 * free a usb stream instance
 */
static void snd_usb_audio_stream_free(struct snd_usb_stream *stream)
{
        free_substream(&stream->substream[0]);
        free_substream(&stream->substream[1]);
        list_del(&stream->list);
        kfree(stream);
}

static void snd_usb_audio_pcm_free(struct snd_pcm *pcm)
{
        struct snd_usb_stream *stream = pcm->private_data;
        if (stream) {
                stream->pcm = NULL;
                snd_usb_audio_stream_free(stream);
        }
}

/*
 * initialize the substream instance.
 */

static 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->tx_length_quirk = as->chip->tx_length_quirk;
        subs->speed = snd_usb_get_speed(subs->dev);
        subs->pkt_offset_adj = 0;

        snd_usb_set_pcm_ops(as->pcm, stream);

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

/* kctl callbacks for usb-audio channel maps */
static int usb_chmap_ctl_info(struct snd_kcontrol *kcontrol,
                              struct snd_ctl_elem_info *uinfo)
{
        struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
        struct snd_usb_substream *subs = info->private_data;

        uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
        uinfo->count = subs->channels_max;
        uinfo->value.integer.min = 0;
        uinfo->value.integer.max = SNDRV_CHMAP_LAST;
        return 0;
}

/* check whether a duplicated entry exists in the audiofmt list */
static bool have_dup_chmap(struct snd_usb_substream *subs,
                           struct audioformat *fp)
{
        struct audioformat *prev = fp;

        list_for_each_entry_continue_reverse(prev, &subs->fmt_list, list) {
                if (prev->chmap &&
                    !memcmp(prev->chmap, fp->chmap, sizeof(*fp->chmap)))
                        return true;
        }
        return false;
}

static int usb_chmap_ctl_tlv(struct snd_kcontrol *kcontrol, int op_flag,
                             unsigned int size, unsigned int __user *tlv)
{
        struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
        struct snd_usb_substream *subs = info->private_data;
        struct audioformat *fp;
        unsigned int __user *dst;
        int count = 0;

        if (size < 8)
                return -ENOMEM;
        if (put_user(SNDRV_CTL_TLVT_CONTAINER, tlv))
                return -EFAULT;
        size -= 8;
        dst = tlv + 2;
        list_for_each_entry(fp, &subs->fmt_list, list) {
                int i, ch_bytes;

                if (!fp->chmap)
                        continue;
                if (have_dup_chmap(subs, fp))
                        continue;
                /* copy the entry */
                ch_bytes = fp->chmap->channels * 4;
                if (size < 8 + ch_bytes)
                        return -ENOMEM;
                if (put_user(SNDRV_CTL_TLVT_CHMAP_FIXED, dst) ||
                    put_user(ch_bytes, dst + 1))
                        return -EFAULT;
                dst += 2;
                for (i = 0; i < fp->chmap->channels; i++, dst++) {
                        if (put_user(fp->chmap->map[i], dst))
                                return -EFAULT;
                }

                count += 8 + ch_bytes;
                size -= 8 + ch_bytes;
        }
        if (put_user(count, tlv + 1))
                return -EFAULT;
        return 0;
}

static int usb_chmap_ctl_get(struct snd_kcontrol *kcontrol,
                             struct snd_ctl_elem_value *ucontrol)
{
        struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
        struct snd_usb_substream *subs = info->private_data;
        struct snd_pcm_chmap_elem *chmap = NULL;
        int i;

        memset(ucontrol->value.integer.value, 0,
               sizeof(ucontrol->value.integer.value));
        if (subs->cur_audiofmt)
                chmap = subs->cur_audiofmt->chmap;
        if (chmap) {
                for (i = 0; i < chmap->channels; i++)
                        ucontrol->value.integer.value[i] = chmap->map[i];
        }
        return 0;
}

/* create a chmap kctl assigned to the given USB substream */
static int add_chmap(struct snd_pcm *pcm, int stream,
                     struct snd_usb_substream *subs)
{
        struct audioformat *fp;
        struct snd_pcm_chmap *chmap;
        struct snd_kcontrol *kctl;
        int err;

        list_for_each_entry(fp, &subs->fmt_list, list)
                if (fp->chmap)
                        goto ok;
        /* no chmap is found */
        return 0;

 ok:
        err = snd_pcm_add_chmap_ctls(pcm, stream, NULL, 0, 0, &chmap);
        if (err < 0)
                return err;

        /* override handlers */
        chmap->private_data = subs;
        kctl = chmap->kctl;
        kctl->info = usb_chmap_ctl_info;
        kctl->get = usb_chmap_ctl_get;
        kctl->tlv.c = usb_chmap_ctl_tlv;

        return 0;
}

/* convert from USB ChannelConfig bits to ALSA chmap element */
static struct snd_pcm_chmap_elem *convert_chmap(int channels, unsigned int bits,
                                                int protocol)
{
        static unsigned int uac1_maps[] = {
                SNDRV_CHMAP_FL,         /* left front */
                SNDRV_CHMAP_FR,         /* right front */
                SNDRV_CHMAP_FC,         /* center front */
                SNDRV_CHMAP_LFE,        /* LFE */
                SNDRV_CHMAP_SL,         /* left surround */
                SNDRV_CHMAP_SR,         /* right surround */
                SNDRV_CHMAP_FLC,        /* left of center */
                SNDRV_CHMAP_FRC,        /* right of center */
                SNDRV_CHMAP_RC,         /* surround */
                SNDRV_CHMAP_SL,         /* side left */
                SNDRV_CHMAP_SR,         /* side right */
                SNDRV_CHMAP_TC,         /* top */
                0 /* terminator */
        };
        static unsigned int uac2_maps[] = {
                SNDRV_CHMAP_FL,         /* front left */
                SNDRV_CHMAP_FR,         /* front right */
                SNDRV_CHMAP_FC,         /* front center */
                SNDRV_CHMAP_LFE,        /* LFE */
                SNDRV_CHMAP_RL,         /* back left */
                SNDRV_CHMAP_RR,         /* back right */
                SNDRV_CHMAP_FLC,        /* front left of center */
                SNDRV_CHMAP_FRC,        /* front right of center */
                SNDRV_CHMAP_RC,         /* back center */
                SNDRV_CHMAP_SL,         /* side left */
                SNDRV_CHMAP_SR,         /* side right */
                SNDRV_CHMAP_TC,         /* top center */
                SNDRV_CHMAP_TFL,        /* top front left */
                SNDRV_CHMAP_TFC,        /* top front center */
                SNDRV_CHMAP_TFR,        /* top front right */
                SNDRV_CHMAP_TRL,        /* top back left */
                SNDRV_CHMAP_TRC,        /* top back center */
                SNDRV_CHMAP_TRR,        /* top back right */
                SNDRV_CHMAP_TFLC,       /* top front left of center */
                SNDRV_CHMAP_TFRC,       /* top front right of center */
                SNDRV_CHMAP_LLFE,       /* left LFE */
                SNDRV_CHMAP_RLFE,       /* right LFE */
                SNDRV_CHMAP_TSL,        /* top side left */
                SNDRV_CHMAP_TSR,        /* top side right */
                SNDRV_CHMAP_BC,         /* bottom center */
                SNDRV_CHMAP_RLC,        /* back left of center */
                SNDRV_CHMAP_RRC,        /* back right of center */
                0 /* terminator */
        };
        struct snd_pcm_chmap_elem *chmap;
        const unsigned int *maps;
        int c;

        if (channels > ARRAY_SIZE(chmap->map))
                return NULL;

        chmap = kzalloc(sizeof(*chmap), GFP_KERNEL);
        if (!chmap)
                return NULL;

        maps = protocol == UAC_VERSION_2 ? uac2_maps : uac1_maps;
        chmap->channels = channels;
        c = 0;

        if (bits) {
                for (; bits && *maps; maps++, bits >>= 1)
                        if (bits & 1)
                                chmap->map[c++] = *maps;
        } else {
                /* If we're missing wChannelConfig, then guess something
                    to make sure the channel map is not skipped entirely */
                if (channels == 1)
                        chmap->map[c++] = SNDRV_CHMAP_MONO;
                else
                        for (; c < channels && *maps; maps++)
                                chmap->map[c++] = *maps;
        }

        for (; c < channels; c++)
                chmap->map[c] = SNDRV_CHMAP_UNKNOWN;

        return chmap;
}

/*
 * add this endpoint to the chip instance.
 * if a stream with the same endpoint already exists, append to it.
 * if not, create a new pcm stream. note, fp is added to the substream
 * fmt_list and will be freed on the chip instance release. do not free
 * fp or do remove it from the substream fmt_list to avoid double-free.
 */
int snd_usb_add_audio_stream(struct snd_usb_audio *chip,
                             int stream,
                             struct audioformat *fp)
{
        struct snd_usb_stream *as;
        struct snd_usb_substream *subs;
        struct snd_pcm *pcm;
        int err;

        list_for_each_entry(as, &chip->pcm_list, list) {
                if (as->fmt_type != fp->fmt_type)
                        continue;
                subs = &as->substream[stream];
                if (subs->ep_num == fp->endpoint) {
                        list_add_tail(&fp->list, &subs->fmt_list);
                        subs->num_formats++;
                        subs->formats |= fp->formats;
                        return 0;
                }
        }
        /* look for an empty stream */
        list_for_each_entry(as, &chip->pcm_list, list) {
                if (as->fmt_type != fp->fmt_type)
                        continue;
                subs = &as->substream[stream];
                if (subs->ep_num)
                        continue;
                err = snd_pcm_new_stream(as->pcm, stream, 1);
                if (err < 0)
                        return err;
                snd_usb_init_substream(as, stream, fp);
                return add_chmap(as->pcm, stream, subs);
        }

        /* create a new pcm */
        as = kzalloc(sizeof(*as), GFP_KERNEL);
        if (!as)
                return -ENOMEM;
        as->pcm_index = chip->pcm_devs;
        as->chip = chip;
        as->fmt_type = fp->fmt_type;
        err = snd_pcm_new(chip->card, "USB Audio", chip->pcm_devs,
                          stream == SNDRV_PCM_STREAM_PLAYBACK ? 1 : 0,
                          stream == SNDRV_PCM_STREAM_PLAYBACK ? 0 : 1,
                          &pcm);
        if (err < 0) {
                kfree(as);
                return err;
        }
        as->pcm = pcm;
        pcm->private_data = as;
        pcm->private_free = snd_usb_audio_pcm_free;
        pcm->info_flags = 0;
        if (chip->pcm_devs > 0)
                sprintf(pcm->name, "USB Audio #%d", chip->pcm_devs);
        else
                strcpy(pcm->name, "USB Audio");

        snd_usb_init_substream(as, stream, fp);

        /*
         * Keep using head insertion for M-Audio Audiophile USB (tm) which has a
         * fix to swap capture stream order in conf/cards/USB-audio.conf
         */
        if (chip->usb_id == USB_ID(0x0763, 0x2003))
                list_add(&as->list, &chip->pcm_list);
        else
                list_add_tail(&as->list, &chip->pcm_list);

        chip->pcm_devs++;

        snd_usb_proc_pcm_format_add(as);

        return add_chmap(pcm, stream, &as->substream[stream]);
}

static int parse_uac_endpoint_attributes(struct snd_usb_audio *chip,
                                         struct usb_host_interface *alts,
                                         int protocol, int iface_no)
{
        /* parsed with a v1 header here. that's ok as we only look at the
         * header first which is the same for both versions */
        struct uac_iso_endpoint_descriptor *csep;
        struct usb_interface_descriptor *altsd = get_iface_desc(alts);
        int attributes = 0;

        csep = snd_usb_find_desc(alts->endpoint[0].extra, alts->endpoint[0].extralen, NULL, USB_DT_CS_ENDPOINT);

        /* Creamware Noah has this descriptor after the 2nd endpoint */
        if (!csep && altsd->bNumEndpoints >= 2)
                csep = snd_usb_find_desc(alts->endpoint[1].extra, alts->endpoint[1].extralen, NULL, USB_DT_CS_ENDPOINT);

        /*
         * If we can't locate the USB_DT_CS_ENDPOINT descriptor in the extra
         * bytes after the first endpoint, go search the entire interface.
         * Some devices have it directly *before* the standard endpoint.
         */
        if (!csep)
                csep = snd_usb_find_desc(alts->extra, alts->extralen, NULL, USB_DT_CS_ENDPOINT);

        if (!csep || csep->bLength < 7 ||
            csep->bDescriptorSubtype != UAC_EP_GENERAL) {
                usb_audio_warn(chip,
                               "%u:%d : no or invalid class specific endpoint descriptor\n",
                               iface_no, altsd->bAlternateSetting);
                return 0;
        }

        if (protocol == UAC_VERSION_1) {
                attributes = csep->bmAttributes;
        } else {
                struct uac2_iso_endpoint_descriptor *csep2 =
                        (struct uac2_iso_endpoint_descriptor *) csep;

                attributes = csep->bmAttributes & UAC_EP_CS_ATTR_FILL_MAX;

                /* emulate the endpoint attributes of a v1 device */
                if (csep2->bmControls & UAC2_CONTROL_PITCH)
                        attributes |= UAC_EP_CS_ATTR_PITCH_CONTROL;
        }

        return attributes;
}

/* find an input terminal descriptor (either UAC1 or UAC2) with the given
 * terminal id
 */
static void *
snd_usb_find_input_terminal_descriptor(struct usb_host_interface *ctrl_iface,
                                               int terminal_id)
{
        struct uac2_input_terminal_descriptor *term = NULL;

        while ((term = snd_usb_find_csint_desc(ctrl_iface->extra,
                                               ctrl_iface->extralen,
                                               term, UAC_INPUT_TERMINAL))) {
                if (term->bTerminalID == terminal_id)
                        return term;
        }

        return NULL;
}

static struct uac2_output_terminal_descriptor *
        snd_usb_find_output_terminal_descriptor(struct usb_host_interface *ctrl_iface,
                                                int terminal_id)
{
        struct uac2_output_terminal_descriptor *term = NULL;

        while ((term = snd_usb_find_csint_desc(ctrl_iface->extra,
                                               ctrl_iface->extralen,
                                               term, UAC_OUTPUT_TERMINAL))) {
                if (term->bTerminalID == terminal_id)
                        return term;
        }

        return NULL;
}

int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
{
        struct usb_device *dev;
        struct usb_interface *iface;
        struct usb_host_interface *alts;
        struct usb_interface_descriptor *altsd;
        int i, altno, err, stream;
        unsigned int format = 0, num_channels = 0;
        struct audioformat *fp = NULL;
        int num, protocol, clock = 0;
        struct uac_format_type_i_continuous_descriptor *fmt;
        unsigned int chconfig;

        dev = chip->dev;

        /* parse the interface's altsettings */
        iface = usb_ifnum_to_if(dev, iface_no);

        num = iface->num_altsetting;

        /*
         * Dallas DS4201 workaround: It presents 5 altsettings, but the last
         * one misses syncpipe, and does not produce any sound.
         */
        if (chip->usb_id == USB_ID(0x04fa, 0x4201))
                num = 4;

        for (i = 0; i < num; i++) {
                alts = &iface->altsetting[i];
                altsd = get_iface_desc(alts);
                protocol = altsd->bInterfaceProtocol;
                /* skip invalid one */
                if (((altsd->bInterfaceClass != USB_CLASS_AUDIO ||
                      (altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIOSTREAMING &&
                       altsd->bInterfaceSubClass != USB_SUBCLASS_VENDOR_SPEC)) &&
                     altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
                    altsd->bNumEndpoints < 1 ||
                    le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) == 0)
                        continue;
                /* must be isochronous */
                if ((get_endpoint(alts, 0)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) !=
                    USB_ENDPOINT_XFER_ISOC)
                        continue;
                /* check direction */
                stream = (get_endpoint(alts, 0)->bEndpointAddress & USB_DIR_IN) ?
                        SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
                altno = altsd->bAlternateSetting;

                if (snd_usb_apply_interface_quirk(chip, iface_no, altno))
                        continue;

                /*
                 * Roland audio streaming interfaces are marked with protocols
                 * 0/1/2, but are UAC 1 compatible.
                 */
                if (USB_ID_VENDOR(chip->usb_id) == 0x0582 &&
                    altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
                    protocol <= 2)
                        protocol = UAC_VERSION_1;

                chconfig = 0;
                /* get audio formats */
                switch (protocol) {
                default:
                        dev_dbg(&dev->dev, "%u:%d: unknown interface protocol %#02x, assuming v1\n",
                                iface_no, altno, protocol);
                        protocol = UAC_VERSION_1;
                        /* fall through */

                case UAC_VERSION_1: {
                        struct uac1_as_header_descriptor *as =
                                snd_usb_find_csint_desc(alts->extra, alts->extralen, NULL, UAC_AS_GENERAL);
                        struct uac_input_terminal_descriptor *iterm;

                        if (!as) {
                                dev_err(&dev->dev,
                                        "%u:%d : UAC_AS_GENERAL descriptor not found\n",
                                        iface_no, altno);
                                continue;
                        }

                        if (as->bLength < sizeof(*as)) {
                                dev_err(&dev->dev,
                                        "%u:%d : invalid UAC_AS_GENERAL desc\n",
                                        iface_no, altno);
                                continue;
                        }

                        format = le16_to_cpu(as->wFormatTag); /* remember the format value */

                        iterm = snd_usb_find_input_terminal_descriptor(chip->ctrl_intf,
                                                                       as->bTerminalLink);
                        if (iterm) {
                                num_channels = iterm->bNrChannels;
                                chconfig = le16_to_cpu(iterm->wChannelConfig);
                        }

                        break;
                }

                case UAC_VERSION_2: {
                        struct uac2_input_terminal_descriptor *input_term;
                        struct uac2_output_terminal_descriptor *output_term;
                        struct uac2_as_header_descriptor *as =
                                snd_usb_find_csint_desc(alts->extra, alts->extralen, NULL, UAC_AS_GENERAL);

                        if (!as) {
                                dev_err(&dev->dev,
                                        "%u:%d : UAC_AS_GENERAL descriptor not found\n",
                                        iface_no, altno);
                                continue;
                        }

                        if (as->bLength < sizeof(*as)) {
                                dev_err(&dev->dev,
                                        "%u:%d : invalid UAC_AS_GENERAL desc\n",
                                        iface_no, altno);
                                continue;
                        }

                        num_channels = as->bNrChannels;
                        format = le32_to_cpu(as->bmFormats);
                        chconfig = le32_to_cpu(as->bmChannelConfig);

                        /* lookup the terminal associated to this interface
                         * to extract the clock */
                        input_term = snd_usb_find_input_terminal_descriptor(chip->ctrl_intf,
                                                                            as->bTerminalLink);
                        if (input_term) {
                                clock = input_term->bCSourceID;
                                if (!chconfig && (num_channels == input_term->bNrChannels))
                                        chconfig = le32_to_cpu(input_term->bmChannelConfig);
                                break;
                        }

                        output_term = snd_usb_find_output_terminal_descriptor(chip->ctrl_intf,
                                                                              as->bTerminalLink);
                        if (output_term) {
                                clock = output_term->bCSourceID;
                                break;
                        }

                        dev_err(&dev->dev,
                                "%u:%d : bogus bTerminalLink %d\n",
                                iface_no, altno, as->bTerminalLink);
                        continue;
                }
                }

                /* get format type */
                fmt = snd_usb_find_csint_desc(alts->extra, alts->extralen, NULL, UAC_FORMAT_TYPE);
                if (!fmt) {
                        dev_err(&dev->dev,
                                "%u:%d : no UAC_FORMAT_TYPE desc\n",
                                iface_no, altno);
                        continue;
                }
                if (((protocol == UAC_VERSION_1) && (fmt->bLength < 8)) ||
                    ((protocol == UAC_VERSION_2) && (fmt->bLength < 6))) {
                        dev_err(&dev->dev,
                                "%u:%d : invalid UAC_FORMAT_TYPE desc\n",
                                iface_no, altno);
                        continue;
                }

                /*
                 * Blue Microphones workaround: The last altsetting is identical
                 * with the previous one, except for a larger packet size, but
                 * is actually a mislabeled two-channel setting; ignore it.
                 */
                if (fmt->bNrChannels == 1 &&
                    fmt->bSubframeSize == 2 &&
                    altno == 2 && num == 3 &&
                    fp && fp->altsetting == 1 && fp->channels == 1 &&
                    fp->formats == SNDRV_PCM_FMTBIT_S16_LE &&
                    protocol == UAC_VERSION_1 &&
                    le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) ==
                                                        fp->maxpacksize * 2)
                        continue;

                fp = kzalloc(sizeof(*fp), GFP_KERNEL);
                if (! fp) {
                        dev_err(&dev->dev, "cannot malloc\n");
                        return -ENOMEM;
                }

                fp->iface = iface_no;
                fp->altsetting = altno;
                fp->altset_idx = i;
                fp->endpoint = get_endpoint(alts, 0)->bEndpointAddress;
                fp->ep_attr = get_endpoint(alts, 0)->bmAttributes;
                fp->datainterval = snd_usb_parse_datainterval(chip, alts);
                fp->protocol = protocol;
                fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
                fp->channels = num_channels;
                if (snd_usb_get_speed(dev) == USB_SPEED_HIGH)
                        fp->maxpacksize = (((fp->maxpacksize >> 11) & 3) + 1)
                                        * (fp->maxpacksize & 0x7ff);
                fp->attributes = parse_uac_endpoint_attributes(chip, alts, protocol, iface_no);
                fp->clock = clock;
                INIT_LIST_HEAD(&fp->list);

                /* some quirks for attributes here */

                switch (chip->usb_id) {
                case USB_ID(0x0a92, 0x0053): /* AudioTrak Optoplay */
                        /* Optoplay sets the sample rate attribute although
                         * it seems not supporting it in fact.
                         */
                        fp->attributes &= ~UAC_EP_CS_ATTR_SAMPLE_RATE;
                        break;
                case USB_ID(0x041e, 0x3020): /* Creative SB Audigy 2 NX */
                case USB_ID(0x0763, 0x2003): /* M-Audio Audiophile USB */
                        /* doesn't set the sample rate attribute, but supports it */
                        fp->attributes |= UAC_EP_CS_ATTR_SAMPLE_RATE;
                        break;
                case USB_ID(0x0763, 0x2001):  /* M-Audio Quattro USB */
                case USB_ID(0x0763, 0x2012):  /* M-Audio Fast Track Pro USB */
                case USB_ID(0x047f, 0x0ca1): /* plantronics headset */
                case USB_ID(0x077d, 0x07af): /* Griffin iMic (note that there is
                                                an older model 77d:223) */
                /*
                 * plantronics headset and Griffin iMic have set adaptive-in
                 * although it's really not...
                 */
                        fp->ep_attr &= ~USB_ENDPOINT_SYNCTYPE;
                        if (stream == SNDRV_PCM_STREAM_PLAYBACK)
                                fp->ep_attr |= USB_ENDPOINT_SYNC_ADAPTIVE;
                        else
                                fp->ep_attr |= USB_ENDPOINT_SYNC_SYNC;
                        break;
                }

                /* ok, let's parse further... */
                if (snd_usb_parse_audio_format(chip, fp, format, fmt, stream) < 0) {
                        kfree(fp->rate_table);
                        kfree(fp);
                        fp = NULL;
                        continue;
                }

                /* Create chmap */
                if (fp->channels != num_channels)
                        chconfig = 0;
                fp->chmap = convert_chmap(fp->channels, chconfig, protocol);

                dev_dbg(&dev->dev, "%u:%d: add audio endpoint %#x\n", iface_no, altno, fp->endpoint);
                err = snd_usb_add_audio_stream(chip, stream, fp);
                if (err < 0) {
                        list_del(&fp->list); /* unlink for avoiding double-free */
                        kfree(fp->rate_table);
                        kfree(fp->chmap);
                        kfree(fp);
                        return err;
                }
                /* try to set the interface... */
                usb_set_interface(chip->dev, iface_no, altno);
                snd_usb_init_pitch(chip, iface_no, alts, fp);
                snd_usb_init_sample_rate(chip, iface_no, alts, fp, fp->rate_max);
        }
        return 0;
}