9 files changed, 396 insertions, 125 deletions

diff --git a/sound/usb/Makefile b/sound/usb/Makefile
index e7ac7f493a8f..1e362bf8834f 100644
--- a/sound/usb/Makefile
+++ b/sound/usb/Makefile
@@ -11,7 +11,8 @@ snd-usb-audio-objs := 	card.o \
                         endpoint.o \
                         urb.o \
                         pcm.o \
-                        helper.o
+                        helper.o \
+                        clock.o
 
 snd-usbmidi-lib-objs := midi.o
 
diff --git a/sound/usb/card.c b/sound/usb/card.c
index da1346bd4856..7a8ac1d81be7 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -236,7 +236,6 @@ static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
         }
 
         case UAC_VERSION_2: {
-                struct uac_clock_source_descriptor *cs;
                 struct usb_interface_assoc_descriptor *assoc =
                         usb_ifnum_to_if(dev, ctrlif)->intf_assoc;
 
@@ -245,21 +244,6 @@ static int snd_usb_create_streams(struct snd_usb_audio *chip, int ctrlif)
                         return -EINVAL;
                 }
 
-                /* FIXME: for now, we expect there is at least one clock source
-                 * descriptor and we always take the first one.
-                 * We should properly support devices with multiple clock sources,
-                 * clock selectors and sample rate conversion units. */
-
-                cs = snd_usb_find_csint_desc(host_iface->extra, host_iface->extralen,
-                                                NULL, UAC2_CLOCK_SOURCE);
-
-                if (!cs) {
-                        snd_printk(KERN_ERR "CLOCK_SOURCE descriptor not found\n");
-                        return -EINVAL;
-                }
-
-                chip->clock_id = cs->bClockID;
-
                 for (i = 0; i < assoc->bInterfaceCount; i++) {
                         int intf = assoc->bFirstInterface + i;
 
@@ -481,6 +465,8 @@ static void *snd_usb_audio_probe(struct usb_device *dev,
                         goto __error;
         }
 
+        chip->ctrl_intf = alts;
+
         if (err > 0) {
                 /* create normal USB audio interfaces */
                 if (snd_usb_create_streams(chip, ifnum) < 0 ||
diff --git a/sound/usb/card.h b/sound/usb/card.h
index ed92420c1095..1febf2f23754 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -25,6 +25,7 @@ struct audioformat {
         unsigned int rate_min, rate_max;        /* min/max rates */
         unsigned int nr_rates;          /* number of rate table entries */
         unsigned int *rate_table;       /* rate table */
+        unsigned char clock;            /* associated clock */
 };
 
 struct snd_usb_substream;
diff --git a/sound/usb/clock.c b/sound/usb/clock.c
new file mode 100644
index 000000000000..b7aadd614c70
--- /dev/null
+++ b/sound/usb/clock.c
@@ -0,0 +1,311 @@
+/*
+ *   Clock domain and sample rate management functions
+ *
+ *   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/bitops.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/usb.h>
+#include <linux/moduleparam.h>
+#include <linux/mutex.h>
+#include <linux/usb/audio.h>
+#include <linux/usb/audio-v2.h>
+
+#include <sound/core.h>
+#include <sound/info.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/initval.h>
+
+#include "usbaudio.h"
+#include "card.h"
+#include "midi.h"
+#include "mixer.h"
+#include "proc.h"
+#include "quirks.h"
+#include "endpoint.h"
+#include "helper.h"
+#include "debug.h"
+#include "pcm.h"
+#include "urb.h"
+#include "format.h"
+
+static struct uac_clock_source_descriptor *
+        snd_usb_find_clock_source(struct usb_host_interface *ctrl_iface,
+                                  int clock_id)
+{
+        struct uac_clock_source_descriptor *cs = NULL;
+
+        while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
+                                             ctrl_iface->extralen,
+                                             cs, UAC2_CLOCK_SOURCE))) {
+                if (cs->bClockID == clock_id)
+                        return cs;
+        }
+
+        return NULL;
+}
+
+static struct uac_clock_selector_descriptor *
+        snd_usb_find_clock_selector(struct usb_host_interface *ctrl_iface,
+                                    int clock_id)
+{
+        struct uac_clock_selector_descriptor *cs = NULL;
+
+        while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
+                                             ctrl_iface->extralen,
+                                             cs, UAC2_CLOCK_SELECTOR))) {
+                if (cs->bClockID == clock_id)
+                        return cs;
+        }
+
+        return NULL;
+}
+
+static struct uac_clock_multiplier_descriptor *
+        snd_usb_find_clock_multiplier(struct usb_host_interface *ctrl_iface,
+                                      int clock_id)
+{
+        struct uac_clock_multiplier_descriptor *cs = NULL;
+
+        while ((cs = snd_usb_find_csint_desc(ctrl_iface->extra,
+                                             ctrl_iface->extralen,
+                                             cs, UAC2_CLOCK_MULTIPLIER))) {
+                if (cs->bClockID == clock_id)
+                        return cs;
+        }
+
+        return NULL;
+}
+
+static int uac_clock_selector_get_val(struct snd_usb_audio *chip, int selector_id)
+{
+        unsigned char buf;
+        int ret;
+
+        ret = snd_usb_ctl_msg(chip->dev, usb_rcvctrlpipe(chip->dev, 0),
+                              UAC2_CS_CUR,
+                              USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
+                              UAC2_CX_CLOCK_SELECTOR << 8, selector_id << 8,
+                              &buf, sizeof(buf), 1000);
+
+        if (ret < 0)
+                return ret;
+
+        return buf;
+}
+
+static bool uac_clock_source_is_valid(struct snd_usb_audio *chip, int source_id)
+{
+        int err;
+        unsigned char data;
+        struct usb_device *dev = chip->dev;
+
+        err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_CUR,
+                              USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
+                              UAC2_CS_CONTROL_CLOCK_VALID << 8, source_id << 8,
+                              &data, sizeof(data), 1000);
+
+        if (err < 0) {
+                snd_printk(KERN_WARNING "%s(): cannot get clock validity for id %d\n",
+                           __func__, source_id);
+                return err;
+        }
+
+        return !!data;
+}
+
+/* Try to find the clock source ID of a given clock entity */
+
+static int __uac_clock_find_source(struct snd_usb_audio *chip,
+                                   struct usb_host_interface *host_iface,
+                                   int entity_id, unsigned long *visited)
+{
+        struct uac_clock_source_descriptor *source;
+        struct uac_clock_selector_descriptor *selector;
+        struct uac_clock_multiplier_descriptor *multiplier;
+
+        entity_id &= 0xff;
+
+        if (test_and_set_bit(entity_id, visited)) {
+                snd_printk(KERN_WARNING
+                        "%s(): recursive clock topology detected, id %d.\n",
+                        __func__, entity_id);
+                return -EINVAL;
+        }
+
+        /* first, see if the ID we're looking for is a clock source already */
+        source = snd_usb_find_clock_source(host_iface, entity_id);
+        if (source)
+                return source->bClockID;
+
+        selector = snd_usb_find_clock_selector(host_iface, entity_id);
+        if (selector) {
+                int ret;
+
+                /* the entity ID we are looking for is a selector.
+                 * find out what it currently selects */
+                ret = uac_clock_selector_get_val(chip, selector->bClockID);
+                if (ret < 0)
+                        return ret;
+
+                if (ret > selector->bNrInPins || ret < 1) {
+                        printk(KERN_ERR
+                                "%s(): selector reported illegal value, id %d, ret %d\n",
+                                __func__, selector->bClockID, ret);
+
+                        return -EINVAL;
+                }
+
+                return __uac_clock_find_source(chip, host_iface,
+                                               selector->baCSourceID[ret-1],
+                                               visited);
+        }
+
+        /* FIXME: multipliers only act as pass-thru element for now */
+        multiplier = snd_usb_find_clock_multiplier(host_iface, entity_id);
+        if (multiplier)
+                return __uac_clock_find_source(chip, host_iface,
+                                               multiplier->bCSourceID, visited);
+
+        return -EINVAL;
+}
+
+int snd_usb_clock_find_source(struct snd_usb_audio *chip,
+                              struct usb_host_interface *host_iface,
+                              int entity_id)
+{
+        DECLARE_BITMAP(visited, 256);
+        memset(visited, 0, sizeof(visited));
+        return __uac_clock_find_source(chip, host_iface, entity_id, visited);
+}
+
+static int set_sample_rate_v1(struct snd_usb_audio *chip, int iface,
+                              struct usb_host_interface *alts,
+                              struct audioformat *fmt, int rate)
+{
+        struct usb_device *dev = chip->dev;
+        unsigned int ep;
+        unsigned char data[3];
+        int err, crate;
+
+        ep = get_endpoint(alts, 0)->bEndpointAddress;
+
+        /* if endpoint doesn't have sampling rate control, bail out */
+        if (!(fmt->attributes & UAC_EP_CS_ATTR_SAMPLE_RATE)) {
+                snd_printk(KERN_WARNING "%d:%d:%d: endpoint lacks sample rate attribute bit, cannot set.\n",
+                                   dev->devnum, iface, fmt->altsetting);
+                return 0;
+        }
+
+        data[0] = rate;
+        data[1] = rate >> 8;
+        data[2] = rate >> 16;
+        if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
+                                   USB_TYPE_CLASS | USB_RECIP_ENDPOINT | USB_DIR_OUT,
+                                   UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep,
+                                   data, sizeof(data), 1000)) < 0) {
+                snd_printk(KERN_ERR "%d:%d:%d: cannot set freq %d to ep %#x\n",
+                           dev->devnum, iface, fmt->altsetting, rate, ep);
+                return err;
+        }
+
+        if ((err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC_GET_CUR,
+                                   USB_TYPE_CLASS | USB_RECIP_ENDPOINT | USB_DIR_IN,
+                                   UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep,
+                                   data, sizeof(data), 1000)) < 0) {
+                snd_printk(KERN_WARNING "%d:%d:%d: cannot get freq at ep %#x\n",
+                           dev->devnum, iface, fmt->altsetting, ep);
+                return 0; /* some devices don't support reading */
+        }
+
+        crate = data[0] | (data[1] << 8) | (data[2] << 16);
+        if (crate != rate) {
+                snd_printd(KERN_WARNING "current rate %d is different from the runtime rate %d\n", crate, rate);
+                // runtime->rate = crate;
+        }
+
+        return 0;
+}
+
+static int set_sample_rate_v2(struct snd_usb_audio *chip, int iface,
+                              struct usb_host_interface *alts,
+                              struct audioformat *fmt, int rate)
+{
+        struct usb_device *dev = chip->dev;
+        unsigned char data[4];
+        int err, crate;
+        int clock = snd_usb_clock_find_source(chip, chip->ctrl_intf, fmt->clock);
+
+        if (clock < 0)
+                return clock;
+
+        if (!uac_clock_source_is_valid(chip, clock)) {
+                snd_printk(KERN_ERR "%d:%d:%d: clock source %d is not valid, cannot use\n",
+                           dev->devnum, iface, fmt->altsetting, clock);
+                return -ENXIO;
+        }
+
+        data[0] = rate;
+        data[1] = rate >> 8;
+        data[2] = rate >> 16;
+        data[3] = rate >> 24;
+        if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC2_CS_CUR,
+                                   USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
+                                   UAC2_CS_CONTROL_SAM_FREQ << 8, clock << 8,
+                                   data, sizeof(data), 1000)) < 0) {
+                snd_printk(KERN_ERR "%d:%d:%d: cannot set freq %d (v2)\n",
+                           dev->devnum, iface, fmt->altsetting, rate);
+                return err;
+        }
+
+        if ((err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_CUR,
+                                   USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
+                                   UAC2_CS_CONTROL_SAM_FREQ << 8, clock << 8,
+                                   data, sizeof(data), 1000)) < 0) {
+                snd_printk(KERN_WARNING "%d:%d:%d: cannot get freq (v2)\n",
+                           dev->devnum, iface, fmt->altsetting);
+                return err;
+        }
+
+        crate = data[0] | (data[1] << 8) | (data[2] << 16) | (data[3] << 24);
+        if (crate != rate)
+                snd_printd(KERN_WARNING "current rate %d is different from the runtime rate %d\n", crate, rate);
+
+        return 0;
+}
+
+int snd_usb_init_sample_rate(struct snd_usb_audio *chip, int iface,
+                             struct usb_host_interface *alts,
+                             struct audioformat *fmt, int rate)
+{
+        struct usb_interface_descriptor *altsd = get_iface_desc(alts);
+
+        switch (altsd->bInterfaceProtocol) {
+        case UAC_VERSION_1:
+                return set_sample_rate_v1(chip, iface, alts, fmt, rate);
+
+        case UAC_VERSION_2:
+                return set_sample_rate_v2(chip, iface, alts, fmt, rate);
+        }
+
+        return -EINVAL;
+}
+
diff --git a/sound/usb/clock.h b/sound/usb/clock.h
new file mode 100644
index 000000000000..beb253684e2d
--- /dev/null
+++ b/sound/usb/clock.h
@@ -0,0 +1,12 @@
+#ifndef __USBAUDIO_CLOCK_H
+#define __USBAUDIO_CLOCK_H
+
+int snd_usb_init_sample_rate(struct snd_usb_audio *chip, int iface,
+                             struct usb_host_interface *alts,
+                             struct audioformat *fmt, int rate);
+
+int snd_usb_clock_find_source(struct snd_usb_audio *chip,
+                              struct usb_host_interface *host_iface,
+                              int entity_id);
+
+#endif /* __USBAUDIO_CLOCK_H */
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 28ee1ce3971a..9593b91452b9 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -190,6 +190,38 @@ static int parse_uac_endpoint_attributes(struct snd_usb_audio *chip,
         return attributes;
 }
 
+static struct uac2_input_terminal_descriptor *
+        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_endpoints(struct snd_usb_audio *chip, int iface_no)
 {
         struct usb_device *dev;
@@ -199,7 +231,7 @@ int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
         int i, altno, err, stream;
         int format = 0, num_channels = 0;
         struct audioformat *fp = NULL;
-        int num, protocol;
+        int num, protocol, clock = 0;
         struct uac_format_type_i_continuous_descriptor *fmt;
 
         dev = chip->dev;
@@ -263,6 +295,8 @@ int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
                 }
 
                 case UAC_VERSION_2: {
+                        struct uac2_input_terminal_descriptor *input_term;
+                        struct uac2_output_terminal_descriptor *output_term;
                         struct uac_as_header_descriptor_v2 *as =
                                 snd_usb_find_csint_desc(alts->extra, alts->extralen, NULL, UAC_AS_GENERAL);
 
@@ -281,7 +315,25 @@ int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
                         num_channels = as->bNrChannels;
                         format = le32_to_cpu(as->bmFormats);
 
-                        break;
+                        /* 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;
+                                break;
+                        }
+
+                        output_term = snd_usb_find_output_terminal_descriptor(chip->ctrl_intf,
+                                                                              as->bTerminalLink);
+                        if (output_term) {
+                                clock = output_term->bCSourceID;
+                                break;
+                        }
+
+                        snd_printk(KERN_ERR "%d:%u:%d : bogus bTerminalLink %d\n",
+                                   dev->devnum, iface_no, altno, as->bTerminalLink);
+                        continue;
                 }
 
                 default:
@@ -338,6 +390,7 @@ int snd_usb_parse_audio_endpoints(struct snd_usb_audio *chip, int iface_no)
                         fp->maxpacksize = (((fp->maxpacksize >> 11) & 3) + 1)
                                         * (fp->maxpacksize & 0x7ff);
                 fp->attributes = parse_uac_endpoint_attributes(chip, alts, protocol, iface_no);
+                fp->clock = clock;
 
                 /* some quirks for attributes here */
 
diff --git a/sound/usb/format.c b/sound/usb/format.c
index fe29d61de19b..5367cd1e52d9 100644
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -29,6 +29,7 @@
 #include "quirks.h"
 #include "helper.h"
 #include "debug.h"
+#include "clock.h"
 
 /*
  * parse the audio format type I descriptor
@@ -215,15 +216,17 @@ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip,
         struct usb_device *dev = chip->dev;
         unsigned char tmp[2], *data;
         int i, nr_rates, data_size, ret = 0;
+        int clock = snd_usb_clock_find_source(chip, chip->ctrl_intf, fp->clock);
 
         /* get the number of sample rates first by only fetching 2 bytes */
         ret = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_RANGE,
                               USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
-                              UAC2_CS_CONTROL_SAM_FREQ << 8, chip->clock_id << 8,
+                              UAC2_CS_CONTROL_SAM_FREQ << 8, clock << 8,
                               tmp, sizeof(tmp), 1000);
 
         if (ret < 0) {
-                snd_printk(KERN_ERR "unable to retrieve number of sample rates\n");
+                snd_printk(KERN_ERR "%s(): unable to retrieve number of sample rates (clock %d)\n",
+                                __func__, clock);
                 goto err;
         }
 
@@ -237,12 +240,13 @@ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip,
 
         /* now get the full information */
         ret = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_RANGE,
-                               USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
-                               UAC2_CS_CONTROL_SAM_FREQ << 8, chip->clock_id << 8,
-                               data, data_size, 1000);
+                              USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
+                              UAC2_CS_CONTROL_SAM_FREQ << 8, clock << 8,
+                              data, data_size, 1000);
 
         if (ret < 0) {
-                snd_printk(KERN_ERR "unable to retrieve sample rate range\n");
+                snd_printk(KERN_ERR "%s(): unable to retrieve sample rate range (clock %d)\n",
+                                __func__, clock);
                 ret = -EINVAL;
                 goto err_free;
         }
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 056587de7be4..456829882f40 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -31,6 +31,7 @@
 #include "urb.h"
 #include "helper.h"
 #include "pcm.h"
+#include "clock.h"
 
 /*
  * return the current pcm pointer.  just based on the hwptr_done value.
@@ -181,103 +182,6 @@ int snd_usb_init_pitch(struct snd_usb_audio *chip, int iface,
         return -EINVAL;
 }
 
-static int set_sample_rate_v1(struct snd_usb_audio *chip, int iface,
-                              struct usb_host_interface *alts,
-                              struct audioformat *fmt, int rate)
-{
-        struct usb_device *dev = chip->dev;
-        unsigned int ep;
-        unsigned char data[3];
-        int err, crate;
-
-        ep = get_endpoint(alts, 0)->bEndpointAddress;
-        /* if endpoint doesn't have sampling rate control, bail out */
-        if (!(fmt->attributes & UAC_EP_CS_ATTR_SAMPLE_RATE)) {
-                snd_printk(KERN_WARNING "%d:%d:%d: endpoint lacks sample rate attribute bit, cannot set.\n",
-                                   dev->devnum, iface, fmt->altsetting);
-                return 0;
-        }
-
-        data[0] = rate;
-        data[1] = rate >> 8;
-        data[2] = rate >> 16;
-        if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
-                                   USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_OUT,
-                                   UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep,
-                                   data, sizeof(data), 1000)) < 0) {
-                snd_printk(KERN_ERR "%d:%d:%d: cannot set freq %d to ep %#x\n",
-                           dev->devnum, iface, fmt->altsetting, rate, ep);
-                return err;
-        }
-        if ((err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC_GET_CUR,
-                                   USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_IN,
-                                   UAC_EP_CS_ATTR_SAMPLE_RATE << 8, ep,
-                                   data, sizeof(data), 1000)) < 0) {
-                snd_printk(KERN_WARNING "%d:%d:%d: cannot get freq at ep %#x\n",
-                           dev->devnum, iface, fmt->altsetting, ep);
-                return 0; /* some devices don't support reading */
-        }
-        crate = data[0] | (data[1] << 8) | (data[2] << 16);
-        if (crate != rate) {
-                snd_printd(KERN_WARNING "current rate %d is different from the runtime rate %d\n", crate, rate);
-                // runtime->rate = crate;
-        }
-
-        return 0;
-}
-
-static int set_sample_rate_v2(struct snd_usb_audio *chip, int iface,
-                              struct usb_host_interface *alts,
-                              struct audioformat *fmt, int rate)
-{
-        struct usb_device *dev = chip->dev;
-        unsigned char data[4];
-        int err, crate;
-
-        data[0] = rate;
-        data[1] = rate >> 8;
-        data[2] = rate >> 16;
-        data[3] = rate >> 24;
-        if ((err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC2_CS_CUR,
-                                   USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
-                                   UAC2_CS_CONTROL_SAM_FREQ << 8, chip->clock_id << 8,
-                                   data, sizeof(data), 1000)) < 0) {
-                snd_printk(KERN_ERR "%d:%d:%d: cannot set freq %d (v2)\n",
-                           dev->devnum, iface, fmt->altsetting, rate);
-                return err;
-        }
-        if ((err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_CUR,
-                                   USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
-                                   UAC2_CS_CONTROL_SAM_FREQ << 8, chip->clock_id << 8,
-                                   data, sizeof(data), 1000)) < 0) {
-                snd_printk(KERN_WARNING "%d:%d:%d: cannot get freq (v2)\n",
-                           dev->devnum, iface, fmt->altsetting);
-                return err;
-        }
-        crate = data[0] | (data[1] << 8) | (data[2] << 16) | (data[3] << 24);
-        if (crate != rate)
-                snd_printd(KERN_WARNING "current rate %d is different from the runtime rate %d\n", crate, rate);
-
-        return 0;
-}
-
-int snd_usb_init_sample_rate(struct snd_usb_audio *chip, int iface,
-                             struct usb_host_interface *alts,
-                             struct audioformat *fmt, int rate)
-{
-        struct usb_interface_descriptor *altsd = get_iface_desc(alts);
-
-        switch (altsd->bInterfaceProtocol) {
-        case UAC_VERSION_1:
-                return set_sample_rate_v1(chip, iface, alts, fmt, rate);
-
-        case UAC_VERSION_2:
-                return set_sample_rate_v2(chip, iface, alts, fmt, rate);
-        }
-
-        return -EINVAL;
-}
-
 /*
  * find a matching format and set up the interface
  */
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index 06ebf24d3a4d..24d3319cc34d 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -40,9 +40,6 @@ struct snd_usb_audio {
         int num_interfaces;
         int num_suspended_intf;
 
-        /* for audio class v2 */
-        int clock_id;
-
         struct list_head pcm_list;      /* list of pcm streams */
         int pcm_devs;
 
@@ -53,6 +50,8 @@ struct snd_usb_audio {
         int setup;                      /* from the 'device_setup' module param */
         int nrpacks;                    /* from the 'nrpacks' module param */
         int async_unlink;               /* from the 'async_unlink' module param */
+
+        struct usb_host_interface *ctrl_intf;   /* the audio control interface */
 };
 
 /*