ALSA: usbaudio: parse USB descriptors with structs

In preparation of support for v2.0 audio class, use the structs from
linux/usb/audio.h and add some new ones to describe the fields that are
actually parsed by the descriptor decoders.

Also, factor out code from usb_create_streams(). This makes it easier to
adopt the new iteration logic needed for v2.0.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

3 files changed, 168 insertions, 99 deletions

diff --git a/include/linux/usb/audio.h b/include/linux/usb/audio.h
index eaf9dffe0a01..44f82d8e09c5 100644
--- a/include/linux/usb/audio.h
+++ b/include/linux/usb/audio.h
@@ -81,7 +81,7 @@
 
 /* Terminal Control Selectors */
 /* 4.3.2  Class-Specific AC Interface Descriptor */
-struct uac_ac_header_descriptor {
+struct uac_ac_header_descriptor_v1 {
         __u8  bLength;                  /* 8 + n */
         __u8  bDescriptorType;          /* USB_DT_CS_INTERFACE */
         __u8  bDescriptorSubtype;       /* UAC_MS_HEADER */
@@ -95,7 +95,7 @@ struct uac_ac_header_descriptor {
 
 /* As above, but more useful for defining your own descriptors: */
 #define DECLARE_UAC_AC_HEADER_DESCRIPTOR(n)                     \
-struct uac_ac_header_descriptor_##n {                           \
+struct uac_ac_header_descriptor_v1_##n {                        \
         __u8  bLength;                                          \
         __u8  bDescriptorType;                                  \
         __u8  bDescriptorSubtype;                               \
@@ -131,7 +131,7 @@ struct uac_input_terminal_descriptor {
 #define UAC_INPUT_TERMINAL_PROC_MICROPHONE_ARRAY        0x206
 
 /* 4.3.2.2 Output Terminal Descriptor */
-struct uac_output_terminal_descriptor {
+struct uac_output_terminal_descriptor_v1 {
         __u8  bLength;                  /* in bytes: 9 */
         __u8  bDescriptorType;          /* CS_INTERFACE descriptor type */
         __u8  bDescriptorSubtype;       /* OUTPUT_TERMINAL descriptor subtype */
@@ -171,7 +171,7 @@ struct uac_feature_unit_descriptor_##ch {			\
 } __attribute__ ((packed))
 
 /* 4.5.2 Class-Specific AS Interface Descriptor */
-struct uac_as_header_descriptor {
+struct uac_as_header_descriptor_v1 {
         __u8  bLength;                  /* in bytes: 7 */
         __u8  bDescriptorType;          /* USB_DT_CS_INTERFACE */
         __u8  bDescriptorSubtype;       /* AS_GENERAL */
@@ -232,6 +232,19 @@ struct uac_format_type_i_discrete_descriptor_##n {		\
 
 #define UAC_FORMAT_TYPE_I_DISCRETE_DESC_SIZE(n) (8 + (n * 3))
 
+/* Formats - Audio Data Format Type I Codes */
+
+struct uac_format_type_ii_discrete_descriptor {
+        __u8 bLength;
+        __u8 bDescriptorType;
+        __u8 bDescriptorSubtype;
+        __u8 bFormatType;
+        __le16 wMaxBitRate;
+        __le16 wSamplesPerFrame;
+        __u8 bSamFreqType;
+        __u8 tSamFreq[][3];
+} __attribute__((packed));
+
 /* Formats - A.2 Format Type Codes */
 #define UAC_FORMAT_TYPE_UNDEFINED       0x0
 #define UAC_FORMAT_TYPE_I               0x1
@@ -253,6 +266,17 @@ struct uac_iso_endpoint_descriptor {
 #define UAC_EP_CS_ATTR_FILL_MAX         0x80
 
 /* A.10.2 Feature Unit Control Selectors */
+
+struct uac_feature_unit_descriptor {
+        __u8 bLength;
+        __u8 bDescriptorType;
+        __u8 bDescriptorSubtype;
+        __u8 bUnitID;
+        __u8 bSourceID;
+        __u8 bControlSize;
+        __u8 controls[0]; /* variable length */
+} __attribute__((packed));
+
 #define UAC_FU_CONTROL_UNDEFINED        0x00
 #define UAC_MUTE_CONTROL                0x01
 #define UAC_VOLUME_CONTROL              0x02
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index c6b9c8cac59e..f833dea60180 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -46,6 +46,8 @@
 #include <linux/usb.h>
 #include <linux/moduleparam.h>
 #include <linux/mutex.h>
+#include <linux/usb/audio.h>
+
 #include <sound/core.h>
 #include <sound/info.h>
 #include <sound/pcm.h>
@@ -2421,15 +2423,17 @@ static int is_big_endian_format(struct snd_usb_audio *chip, struct audioformat *
  * @fmt: the format type descriptor
  */
 static int parse_audio_format_i_type(struct snd_usb_audio *chip, struct audioformat *fp,
-                                     int format, unsigned char *fmt)
+                                     int format, void *fmt_raw)
 {
         int pcm_format;
         int sample_width, sample_bytes;
+        struct uac_format_type_i_discrete_descriptor *fmt = fmt_raw;
 
         /* FIXME: correct endianess and sign? */
         pcm_format = -1;
-        sample_width = fmt[6];
-        sample_bytes = fmt[5];
+        sample_width = fmt->bBitResolution;
+        sample_bytes = fmt->bSubframeSize;
+
         switch (format) {
         case 0: /* some devices don't define this correctly... */
                 snd_printdd(KERN_INFO "%d:%u:%d : format type 0 is detected, processed as PCM\n",
@@ -2442,7 +2446,7 @@ static int parse_audio_format_i_type(struct snd_usb_audio *chip, struct audiofor
                                    sample_width, sample_bytes);
                 }
                 /* check the format byte size */
-                switch (fmt[5]) {
+                switch (sample_bytes) {
                 case 1:
                         pcm_format = SNDRV_PCM_FORMAT_S8;
                         break;
@@ -2463,8 +2467,8 @@ static int parse_audio_format_i_type(struct snd_usb_audio *chip, struct audiofor
                         break;
                 default:
                         snd_printk(KERN_INFO "%d:%u:%d : unsupported sample bitwidth %d in %d bytes\n",
-                                   chip->dev->devnum, fp->iface,
-                                   fp->altsetting, sample_width, sample_bytes);
+                                   chip->dev->devnum, fp->iface, fp->altsetting,
+                                   sample_width, sample_bytes);
                         break;
                 }
                 break;
@@ -2564,11 +2568,12 @@ static int parse_audio_format_rates(struct snd_usb_audio *chip, struct audioform
  * parse the format type I and III descriptors
  */
 static int parse_audio_format_i(struct snd_usb_audio *chip, struct audioformat *fp,
-                                int format, unsigned char *fmt)
+                                int format, void *fmt_raw)
 {
         int pcm_format;
+        struct uac_format_type_i_discrete_descriptor *fmt = fmt_raw;
 
-        if (fmt[3] == USB_FORMAT_TYPE_III) {
+        if (fmt->bFormatType == USB_FORMAT_TYPE_III) {
                 /* FIXME: the format type is really IECxxx
                  *        but we give normal PCM format to get the existing
                  *        apps working...
@@ -2590,23 +2595,27 @@ static int parse_audio_format_i(struct snd_usb_audio *chip, struct audioformat *
                 if (pcm_format < 0)
                         return -1;
         }
+
         fp->format = pcm_format;
-        fp->channels = fmt[4];
+        fp->channels = fmt->bNrChannels;
+
         if (fp->channels < 1) {
                 snd_printk(KERN_ERR "%d:%u:%d : invalid channels %d\n",
                            chip->dev->devnum, fp->iface, fp->altsetting, fp->channels);
                 return -1;
         }
-        return parse_audio_format_rates(chip, fp, fmt, 7);
+        return parse_audio_format_rates(chip, fp, fmt_raw, 7);
 }
 
 /*
- * prase the format type II descriptor
+ * parse the format type II descriptor
  */
 static int parse_audio_format_ii(struct snd_usb_audio *chip, struct audioformat *fp,
-                                 int format, unsigned char *fmt)
+                                 int format, void *fmt_raw)
 {
         int brate, framesize;
+        struct uac_format_type_ii_discrete_descriptor *fmt = fmt_raw;
+
         switch (format) {
         case USB_AUDIO_FORMAT_AC3:
                 /* FIXME: there is no AC3 format defined yet */
@@ -2622,20 +2631,25 @@ static int parse_audio_format_ii(struct snd_usb_audio *chip, struct audioformat
                 fp->format = SNDRV_PCM_FORMAT_MPEG;
                 break;
         }
+
         fp->channels = 1;
-        brate = combine_word(&fmt[4]);  /* fmt[4,5] : wMaxBitRate (in kbps) */
-        framesize = combine_word(&fmt[6]); /* fmt[6,7]: wSamplesPerFrame */
+
+        brate = le16_to_cpu(fmt->wMaxBitRate);
+        framesize = le16_to_cpu(fmt->wSamplesPerFrame);
         snd_printd(KERN_INFO "found format II with max.bitrate = %d, frame size=%d\n", brate, framesize);
         fp->frame_size = framesize;
-        return parse_audio_format_rates(chip, fp, fmt, 8); /* fmt[8..] sample rates */
+        return parse_audio_format_rates(chip, fp, fmt_raw, 8); /* fmt[8..] sample rates */
 }
 
 static int parse_audio_format(struct snd_usb_audio *chip, struct audioformat *fp,
-                              int format, unsigned char *fmt, int stream)
+                              int format, void *fmt_raw, int stream)
 {
         int err;
+        /* we only parse the common header of all format types here,
+         * so it is safe to take a type_i struct */
+        struct uac_format_type_i_discrete_descriptor *fmt = fmt_raw;
 
-        switch (fmt[3]) {
+        switch (fmt->bFormatType) {
         case USB_FORMAT_TYPE_I:
         case USB_FORMAT_TYPE_III:
                 err = parse_audio_format_i(chip, fp, format, fmt);
@@ -2645,10 +2659,10 @@ static int parse_audio_format(struct snd_usb_audio *chip, struct audioformat *fp
                 break;
         default:
                 snd_printd(KERN_INFO "%d:%u:%d : format type %d is not supported yet\n",
-                           chip->dev->devnum, fp->iface, fp->altsetting, fmt[3]);
+                           chip->dev->devnum, fp->iface, fp->altsetting, fmt->bFormatType);
                 return -1;
         }
-        fp->fmt_type = fmt[3];
+        fp->fmt_type = fmt->bFormatType;
         if (err < 0)
                 return err;
 #if 1
@@ -2659,7 +2673,7 @@ static int parse_audio_format(struct snd_usb_audio *chip, struct audioformat *fp
         if (chip->usb_id == USB_ID(0x041e, 0x3000) ||
             chip->usb_id == USB_ID(0x041e, 0x3020) ||
             chip->usb_id == USB_ID(0x041e, 0x3061)) {
-                if (fmt[3] == USB_FORMAT_TYPE_I &&
+                if (fmt->bFormatType == USB_FORMAT_TYPE_I &&
                     fp->rates != SNDRV_PCM_RATE_48000 &&
                     fp->rates != SNDRV_PCM_RATE_96000)
                         return -1;
@@ -2708,6 +2722,8 @@ static int parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
                 num = 4;
 
         for (i = 0; i < num; i++) {
+                struct uac_as_header_descriptor_v1 *as;
+
                 alts = &iface->altsetting[i];
                 altsd = get_iface_desc(alts);
                 /* skip invalid one */
@@ -2726,7 +2742,7 @@ static int parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
                 stream = (get_endpoint(alts, 0)->bEndpointAddress & USB_DIR_IN) ?
                         SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
                 altno = altsd->bAlternateSetting;
-        
+
                 /* audiophile usb: skip altsets incompatible with device_setup
                  */
                 if (chip->usb_id == USB_ID(0x0763, 0x2003) && 
@@ -2734,20 +2750,21 @@ static int parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
                         continue;
 
                 /* get audio formats */
-                fmt = snd_usb_find_csint_desc(alts->extra, alts->extralen, NULL, AS_GENERAL);
-                if (!fmt) {
+                as = snd_usb_find_csint_desc(alts->extra, alts->extralen, NULL, AS_GENERAL);
+
+                if (!as) {
                         snd_printk(KERN_ERR "%d:%u:%d : AS_GENERAL descriptor not found\n",
                                    dev->devnum, iface_no, altno);
                         continue;
                 }
 
-                if (fmt[0] < 7) {
+                if (as->bLength < sizeof(*as)) {
                         snd_printk(KERN_ERR "%d:%u:%d : invalid AS_GENERAL desc\n",
                                    dev->devnum, iface_no, altno);
                         continue;
                 }
 
-                format = (fmt[6] << 8) | fmt[5]; /* remember the format value */
+                format = le16_to_cpu(as->wFormatTag); /* remember the format value */
 
                 /* get format type */
                 fmt = snd_usb_find_csint_desc(alts->extra, alts->extralen, NULL, FORMAT_TYPE);
@@ -2875,6 +2892,65 @@ static void snd_usb_stream_disconnect(struct list_head *head)
         }
 }
 
+static int snd_usb_create_stream(struct snd_usb_audio *chip, int ctrlif, int interface)
+{
+        struct usb_device *dev = chip->dev;
+        struct usb_host_interface *alts;
+        struct usb_interface_descriptor *altsd;
+        struct usb_interface *iface = usb_ifnum_to_if(dev, interface);
+
+        if (!iface) {
+                snd_printk(KERN_ERR "%d:%u:%d : does not exist\n",
+                           dev->devnum, ctrlif, interface);
+                return -EINVAL;
+        }
+
+        if (usb_interface_claimed(iface)) {
+                snd_printdd(KERN_INFO "%d:%d:%d: skipping, already claimed\n",
+                                                dev->devnum, ctrlif, interface);
+                return -EINVAL;
+        }
+
+        alts = &iface->altsetting[0];
+        altsd = get_iface_desc(alts);
+        if ((altsd->bInterfaceClass == USB_CLASS_AUDIO ||
+             altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC) &&
+            altsd->bInterfaceSubClass == USB_SUBCLASS_MIDI_STREAMING) {
+                int err = snd_usbmidi_create(chip->card, iface,
+                                             &chip->midi_list, NULL);
+                if (err < 0) {
+                        snd_printk(KERN_ERR "%d:%u:%d: cannot create sequencer device\n",
+                                                dev->devnum, ctrlif, interface);
+                        return -EINVAL;
+                }
+                usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
+
+                return 0;
+        }
+
+        if ((altsd->bInterfaceClass != USB_CLASS_AUDIO &&
+             altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
+            altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIO_STREAMING) {
+                snd_printdd(KERN_ERR "%d:%u:%d: skipping non-supported interface %d\n",
+                                        dev->devnum, ctrlif, interface, altsd->bInterfaceClass);
+                /* skip non-supported classes */
+                return -EINVAL;
+        }
+
+        if (snd_usb_get_speed(dev) == USB_SPEED_LOW) {
+                snd_printk(KERN_ERR "low speed audio streaming not supported\n");
+                return -EINVAL;
+        }
+
+        if (! parse_audio_endpoints(chip, interface)) {
+                usb_set_interface(dev, interface, 0); /* reset the current interface */
+                usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
 /*
  * parse audio control descriptor and create pcm/midi streams
  */
@@ -2882,69 +2958,36 @@ static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
 {
         struct usb_device *dev = chip->dev;
         struct usb_host_interface *host_iface;
-        struct usb_interface *iface;
-        unsigned char *p1;
-        int i, j;
+        struct uac_ac_header_descriptor_v1 *h1;
+        void *control_header;
+        int i;
 
         /* find audiocontrol interface */
         host_iface = &usb_ifnum_to_if(dev, ctrlif)->altsetting[0];
-        if (!(p1 = snd_usb_find_csint_desc(host_iface->extra, host_iface->extralen, NULL, HEADER))) {
+        control_header = snd_usb_find_csint_desc(host_iface->extra,
+                                                 host_iface->extralen,
+                                                 NULL, HEADER);
+
+        if (!control_header) {
                 snd_printk(KERN_ERR "cannot find HEADER\n");
                 return -EINVAL;
         }
-        if (! p1[7] || p1[0] < 8 + p1[7]) {
-                snd_printk(KERN_ERR "invalid HEADER\n");
+
+        h1 = control_header;
+
+        if (!h1->bInCollection) {
+                snd_printk(KERN_INFO "skipping empty audio interface (v1)\n");
                 return -EINVAL;
         }
 
-        /*
-         * parse all USB audio streaming interfaces
-         */
-        for (i = 0; i < p1[7]; i++) {
-                struct usb_host_interface *alts;
-                struct usb_interface_descriptor *altsd;
-                j = p1[8 + i];
-                iface = usb_ifnum_to_if(dev, j);
-                if (!iface) {
-                        snd_printk(KERN_ERR "%d:%u:%d : does not exist\n",
-                                   dev->devnum, ctrlif, j);
-                        continue;
-                }
-                if (usb_interface_claimed(iface)) {
-                        snd_printdd(KERN_INFO "%d:%d:%d: skipping, already claimed\n", dev->devnum, ctrlif, j);
-                        continue;
-                }
-                alts = &iface->altsetting[0];
-                altsd = get_iface_desc(alts);
-                if ((altsd->bInterfaceClass == USB_CLASS_AUDIO ||
-                     altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC) &&
-                    altsd->bInterfaceSubClass == USB_SUBCLASS_MIDI_STREAMING) {
-                        int err = snd_usbmidi_create(chip->card, iface,
-                                                     &chip->midi_list, NULL);
-                        if (err < 0) {
-                                snd_printk(KERN_ERR "%d:%u:%d: cannot create sequencer device\n", dev->devnum, ctrlif, j);
-                                continue;
-                        }
-                        usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
-                        continue;
-                }
-                if ((altsd->bInterfaceClass != USB_CLASS_AUDIO &&
-                     altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
-                    altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIO_STREAMING) {
-                        snd_printdd(KERN_ERR "%d:%u:%d: skipping non-supported interface %d\n", dev->devnum, ctrlif, j, altsd->bInterfaceClass);
-                        /* skip non-supported classes */
-                        continue;
-                }
-                if (snd_usb_get_speed(dev) == USB_SPEED_LOW) {
-                        snd_printk(KERN_ERR "low speed audio streaming not supported\n");
-                        continue;
-                }
-                if (! parse_audio_endpoints(chip, j)) {
-                        usb_set_interface(dev, j, 0); /* reset the current interface */
-                        usb_driver_claim_interface(&usb_audio_driver, iface, (void *)-1L);
-                }
+        if (h1->bLength < sizeof(*h1) + h1->bInCollection) {
+                snd_printk(KERN_ERR "invalid HEADER (v1)\n");
+                return -EINVAL;
         }
 
+        for (i = 0; i < h1->bInCollection; i++)
+                snd_usb_create_stream(chip, ctrlif, h1->baInterfaceNr[i]);
+
         return 0;
 }
 
@@ -3607,7 +3650,6 @@ static void *snd_usb_audio_probe(struct usb_device *dev,
         ifnum = get_iface_desc(alts)->bInterfaceNumber;
         id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
                     le16_to_cpu(dev->descriptor.idProduct));
-
         if (quirk && quirk->ifnum >= 0 && ifnum != quirk->ifnum)
                 goto __err_val;
 
diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c
index 35b4830fb0c4..11636a6112d5 100644
--- a/sound/usb/usbmixer.c
+++ b/sound/usb/usbmixer.c
@@ -32,6 +32,8 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/usb.h>
+#include <linux/usb/audio.h>
+
 #include <sound/core.h>
 #include <sound/control.h>
 #include <sound/hwdep.h>
@@ -1086,29 +1088,30 @@ static void build_feature_ctl(struct mixer_build *state, unsigned char *desc,
  *
  * most of controlls are defined here.
  */
-static int parse_audio_feature_unit(struct mixer_build *state, int unitid, unsigned char *ftr)
+static int parse_audio_feature_unit(struct mixer_build *state, int unitid, void *_ftr)
 {
         int channels, i, j;
         struct usb_audio_term iterm;
         unsigned int master_bits, first_ch_bits;
         int err, csize;
+        struct uac_feature_unit_descriptor *ftr = _ftr;
 
-        if (ftr[0] < 7 || ! (csize = ftr[5]) || ftr[0] < 7 + csize) {
+        if (ftr->bLength < 7 || ! (csize = ftr->bControlSize) || ftr->bLength < 7 + csize) {
                 snd_printk(KERN_ERR "usbaudio: unit %u: invalid FEATURE_UNIT descriptor\n", unitid);
                 return -EINVAL;
         }
 
         /* parse the source unit */
-        if ((err = parse_audio_unit(state, ftr[4])) < 0)
+        if ((err = parse_audio_unit(state, ftr->bSourceID)) < 0)
                 return err;
 
         /* determine the input source type and name */
-        if (check_input_term(state, ftr[4], &iterm) < 0)
+        if (check_input_term(state, ftr->bSourceID, &iterm) < 0)
                 return -EINVAL;
 
-        channels = (ftr[0] - 7) / csize - 1;
+        channels = (ftr->bLength - 7) / csize - 1;
 
-        master_bits = snd_usb_combine_bytes(ftr + 6, csize);
+        master_bits = snd_usb_combine_bytes(ftr->controls, csize);
         /* master configuration quirks */
         switch (state->chip->usb_id) {
         case USB_ID(0x08bb, 0x2702):
@@ -1119,21 +1122,21 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, unsig
                 break;
         }
         if (channels > 0)
-                first_ch_bits = snd_usb_combine_bytes(ftr + 6 + csize, csize);
+                first_ch_bits = snd_usb_combine_bytes(ftr->controls + csize, csize);
         else
                 first_ch_bits = 0;
         /* check all control types */
         for (i = 0; i < 10; i++) {
                 unsigned int ch_bits = 0;
                 for (j = 0; j < channels; j++) {
-                        unsigned int mask = snd_usb_combine_bytes(ftr + 6 + csize * (j+1), csize);
+                        unsigned int mask = snd_usb_combine_bytes(ftr->controls + csize * (j+1), csize);
                         if (mask & (1 << i))
                                 ch_bits |= (1 << j);
                 }
                 if (ch_bits & 1) /* the first channel must be set (for ease of programming) */
-                        build_feature_ctl(state, ftr, ch_bits, i, &iterm, unitid);
+                        build_feature_ctl(state, _ftr, ch_bits, i, &iterm, unitid);
                 if (master_bits & (1 << i))
-                        build_feature_ctl(state, ftr, 0, i, &iterm, unitid);
+                        build_feature_ctl(state, _ftr, 0, i, &iterm, unitid);
         }
 
         return 0;
@@ -1780,7 +1783,7 @@ static int snd_usb_mixer_dev_free(struct snd_device *device)
  */
 static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)
 {
-        unsigned char *desc;
+        struct uac_output_terminal_descriptor_v1 *desc;
         struct mixer_build state;
         int err;
         const struct usbmix_ctl_map *map;
@@ -1805,13 +1808,13 @@ static int snd_usb_mixer_controls(struct usb_mixer_interface *mixer)
 
         desc = NULL;
         while ((desc = snd_usb_find_csint_desc(hostif->extra, hostif->extralen, desc, OUTPUT_TERMINAL)) != NULL) {
-                if (desc[0] < 9)
+                if (desc->bLength < 9)
                         continue; /* invalid descriptor? */
-                set_bit(desc[3], state.unitbitmap);  /* mark terminal ID as visited */
-                state.oterm.id = desc[3];
-                state.oterm.type = combine_word(&desc[4]);
-                state.oterm.name = desc[8];
-                err = parse_audio_unit(&state, desc[7]);
+                set_bit(desc->bTerminalID, state.unitbitmap);  /* mark terminal ID as visited */
+                state.oterm.id = desc->bTerminalID;
+                state.oterm.type = le16_to_cpu(desc->wTerminalType);
+                state.oterm.name = desc->iTerminal;
+                err = parse_audio_unit(&state, desc->bSourceID);
                 if (err < 0)
                         return err;
         }