2 * (Tentative) USB Audio Driver for ALSA
4 * Copyright (c) 2002 by Takashi Iwai <tiwai@suse.de>
6 * Many codes borrowed from audio.c by
7 * Alan Cox (alan@lxorguk.ukuu.org.uk)
8 * Thomas Sailer (sailer@ife.ee.ethz.ch)
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
28 * - the linked URBs would be preferred but not used so far because of
29 * the instability of unlinking.
30 * - type II is not supported properly. there is no device which supports
31 * this type *correctly*. SB extigy looks as if it supports, but it's
32 * indeed an AC3 stream packed in SPDIF frames (i.e. no real AC3 stream).
36 #include <linux/bitops.h>
37 #include <linux/init.h>
38 #include <linux/list.h>
39 #include <linux/slab.h>
40 #include <linux/string.h>
41 #include <linux/ctype.h>
42 #include <linux/usb.h>
43 #include <linux/moduleparam.h>
44 #include <linux/mutex.h>
45 #include <linux/usb/audio.h>
46 #include <linux/usb/audio-v2.h>
47 #include <linux/module.h>
49 #include <sound/control.h>
50 #include <sound/core.h>
51 #include <sound/info.h>
52 #include <sound/pcm.h>
53 #include <sound/pcm_params.h>
54 #include <sound/initval.h>
70 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
71 MODULE_DESCRIPTION("USB Audio");
72 MODULE_LICENSE("GPL");
73 MODULE_SUPPORTED_DEVICE("{{Generic,USB Audio}}");
76 static int index
[SNDRV_CARDS
] = SNDRV_DEFAULT_IDX
; /* Index 0-MAX */
77 static char *id
[SNDRV_CARDS
] = SNDRV_DEFAULT_STR
; /* ID for this card */
78 static bool enable
[SNDRV_CARDS
] = SNDRV_DEFAULT_ENABLE_PNP
;/* Enable this card */
79 /* Vendor/product IDs for this card */
80 static int vid
[SNDRV_CARDS
] = { [0 ... (SNDRV_CARDS
-1)] = -1 };
81 static int pid
[SNDRV_CARDS
] = { [0 ... (SNDRV_CARDS
-1)] = -1 };
82 static int device_setup
[SNDRV_CARDS
]; /* device parameter for this card */
83 static bool ignore_ctl_error
;
84 static bool autoclock
= true;
86 module_param_array(index
, int, NULL
, 0444);
87 MODULE_PARM_DESC(index
, "Index value for the USB audio adapter.");
88 module_param_array(id
, charp
, NULL
, 0444);
89 MODULE_PARM_DESC(id
, "ID string for the USB audio adapter.");
90 module_param_array(enable
, bool, NULL
, 0444);
91 MODULE_PARM_DESC(enable
, "Enable USB audio adapter.");
92 module_param_array(vid
, int, NULL
, 0444);
93 MODULE_PARM_DESC(vid
, "Vendor ID for the USB audio device.");
94 module_param_array(pid
, int, NULL
, 0444);
95 MODULE_PARM_DESC(pid
, "Product ID for the USB audio device.");
96 module_param_array(device_setup
, int, NULL
, 0444);
97 MODULE_PARM_DESC(device_setup
, "Specific device setup (if needed).");
98 module_param(ignore_ctl_error
, bool, 0444);
99 MODULE_PARM_DESC(ignore_ctl_error
,
100 "Ignore errors from USB controller for mixer interfaces.");
101 module_param(autoclock
, bool, 0444);
102 MODULE_PARM_DESC(autoclock
, "Enable auto-clock selection for UAC2 devices (default: yes).");
105 * we keep the snd_usb_audio_t instances by ourselves for merging
106 * the all interfaces on the same card as one sound device.
109 static DEFINE_MUTEX(register_mutex
);
110 static struct snd_usb_audio
*usb_chip
[SNDRV_CARDS
];
111 static struct usb_driver usb_audio_driver
;
115 * called from usb_audio_disconnect()
117 static void snd_usb_stream_disconnect(struct snd_usb_stream
*as
)
120 struct snd_usb_substream
*subs
;
122 for (idx
= 0; idx
< 2; idx
++) {
123 subs
= &as
->substream
[idx
];
124 if (!subs
->num_formats
)
126 subs
->interface
= -1;
127 subs
->data_endpoint
= NULL
;
128 subs
->sync_endpoint
= NULL
;
132 static int snd_usb_create_stream(struct snd_usb_audio
*chip
, int ctrlif
, int interface
)
134 struct usb_device
*dev
= chip
->dev
;
135 struct usb_host_interface
*alts
;
136 struct usb_interface_descriptor
*altsd
;
137 struct usb_interface
*iface
= usb_ifnum_to_if(dev
, interface
);
140 dev_err(&dev
->dev
, "%u:%d : does not exist\n",
145 alts
= &iface
->altsetting
[0];
146 altsd
= get_iface_desc(alts
);
149 * Android with both accessory and audio interfaces enabled gets the
150 * interface numbers wrong.
152 if ((chip
->usb_id
== USB_ID(0x18d1, 0x2d04) ||
153 chip
->usb_id
== USB_ID(0x18d1, 0x2d05)) &&
155 altsd
->bInterfaceClass
== USB_CLASS_VENDOR_SPEC
&&
156 altsd
->bInterfaceSubClass
== USB_SUBCLASS_VENDOR_SPEC
) {
158 iface
= usb_ifnum_to_if(dev
, interface
);
161 alts
= &iface
->altsetting
[0];
162 altsd
= get_iface_desc(alts
);
165 if (usb_interface_claimed(iface
)) {
166 dev_dbg(&dev
->dev
, "%d:%d: skipping, already claimed\n",
171 if ((altsd
->bInterfaceClass
== USB_CLASS_AUDIO
||
172 altsd
->bInterfaceClass
== USB_CLASS_VENDOR_SPEC
) &&
173 altsd
->bInterfaceSubClass
== USB_SUBCLASS_MIDISTREAMING
) {
174 int err
= snd_usbmidi_create(chip
->card
, iface
,
175 &chip
->midi_list
, NULL
);
178 "%u:%d: cannot create sequencer device\n",
182 usb_driver_claim_interface(&usb_audio_driver
, iface
, (void *)-1L);
187 if ((altsd
->bInterfaceClass
!= USB_CLASS_AUDIO
&&
188 altsd
->bInterfaceClass
!= USB_CLASS_VENDOR_SPEC
) ||
189 altsd
->bInterfaceSubClass
!= USB_SUBCLASS_AUDIOSTREAMING
) {
191 "%u:%d: skipping non-supported interface %d\n",
192 ctrlif
, interface
, altsd
->bInterfaceClass
);
193 /* skip non-supported classes */
197 if (snd_usb_get_speed(dev
) == USB_SPEED_LOW
) {
198 dev_err(&dev
->dev
, "low speed audio streaming not supported\n");
202 if (! snd_usb_parse_audio_interface(chip
, interface
)) {
203 usb_set_interface(dev
, interface
, 0); /* reset the current interface */
204 usb_driver_claim_interface(&usb_audio_driver
, iface
, (void *)-1L);
212 * parse audio control descriptor and create pcm/midi streams
214 static int snd_usb_create_streams(struct snd_usb_audio
*chip
, int ctrlif
)
216 struct usb_device
*dev
= chip
->dev
;
217 struct usb_host_interface
*host_iface
;
218 struct usb_interface_descriptor
*altsd
;
219 void *control_header
;
222 /* find audiocontrol interface */
223 host_iface
= &usb_ifnum_to_if(dev
, ctrlif
)->altsetting
[0];
224 control_header
= snd_usb_find_csint_desc(host_iface
->extra
,
225 host_iface
->extralen
,
227 altsd
= get_iface_desc(host_iface
);
228 protocol
= altsd
->bInterfaceProtocol
;
230 if (!control_header
) {
231 dev_err(&dev
->dev
, "cannot find UAC_HEADER\n");
238 "unknown interface protocol %#02x, assuming v1\n",
242 case UAC_VERSION_1
: {
243 struct uac1_ac_header_descriptor
*h1
= control_header
;
245 if (!h1
->bInCollection
) {
246 dev_info(&dev
->dev
, "skipping empty audio interface (v1)\n");
250 if (h1
->bLength
< sizeof(*h1
) + h1
->bInCollection
) {
251 dev_err(&dev
->dev
, "invalid UAC_HEADER (v1)\n");
255 for (i
= 0; i
< h1
->bInCollection
; i
++)
256 snd_usb_create_stream(chip
, ctrlif
, h1
->baInterfaceNr
[i
]);
261 case UAC_VERSION_2
: {
262 struct usb_interface_assoc_descriptor
*assoc
=
263 usb_ifnum_to_if(dev
, ctrlif
)->intf_assoc
;
267 * Firmware writers cannot count to three. So to find
268 * the IAD on the NuForce UDH-100, also check the next
271 struct usb_interface
*iface
=
272 usb_ifnum_to_if(dev
, ctrlif
+ 1);
275 iface
->intf_assoc
->bFunctionClass
== USB_CLASS_AUDIO
&&
276 iface
->intf_assoc
->bFunctionProtocol
== UAC_VERSION_2
)
277 assoc
= iface
->intf_assoc
;
281 dev_err(&dev
->dev
, "Audio class v2 interfaces need an interface association\n");
285 for (i
= 0; i
< assoc
->bInterfaceCount
; i
++) {
286 int intf
= assoc
->bFirstInterface
+ i
;
289 snd_usb_create_stream(chip
, ctrlif
, intf
);
300 * free the chip instance
302 * here we have to do not much, since pcm and controls are already freed
306 static int snd_usb_audio_free(struct snd_usb_audio
*chip
)
308 struct snd_usb_endpoint
*ep
, *n
;
310 list_for_each_entry_safe(ep
, n
, &chip
->ep_list
, list
)
311 snd_usb_endpoint_free(ep
);
313 mutex_destroy(&chip
->mutex
);
318 static int snd_usb_audio_dev_free(struct snd_device
*device
)
320 struct snd_usb_audio
*chip
= device
->device_data
;
321 return snd_usb_audio_free(chip
);
325 * create a chip instance and set its names.
327 static int snd_usb_audio_create(struct usb_interface
*intf
,
328 struct usb_device
*dev
, int idx
,
329 const struct snd_usb_audio_quirk
*quirk
,
330 struct snd_usb_audio
**rchip
)
332 struct snd_card
*card
;
333 struct snd_usb_audio
*chip
;
336 static struct snd_device_ops ops
= {
337 .dev_free
= snd_usb_audio_dev_free
,
342 switch (snd_usb_get_speed(dev
)) {
346 case USB_SPEED_WIRELESS
:
347 case USB_SPEED_SUPER
:
350 dev_err(&dev
->dev
, "unknown device speed %d\n", snd_usb_get_speed(dev
));
354 err
= snd_card_new(&intf
->dev
, index
[idx
], id
[idx
], THIS_MODULE
,
357 dev_err(&dev
->dev
, "cannot create card instance %d\n", idx
);
361 chip
= kzalloc(sizeof(*chip
), GFP_KERNEL
);
367 mutex_init(&chip
->mutex
);
368 init_waitqueue_head(&chip
->shutdown_wait
);
372 chip
->setup
= device_setup
[idx
];
373 chip
->autoclock
= autoclock
;
374 atomic_set(&chip
->active
, 1); /* avoid autopm during probing */
375 atomic_set(&chip
->usage_count
, 0);
376 atomic_set(&chip
->shutdown
, 0);
378 chip
->usb_id
= USB_ID(le16_to_cpu(dev
->descriptor
.idVendor
),
379 le16_to_cpu(dev
->descriptor
.idProduct
));
380 INIT_LIST_HEAD(&chip
->pcm_list
);
381 INIT_LIST_HEAD(&chip
->ep_list
);
382 INIT_LIST_HEAD(&chip
->midi_list
);
383 INIT_LIST_HEAD(&chip
->mixer_list
);
385 if ((err
= snd_device_new(card
, SNDRV_DEV_LOWLEVEL
, chip
, &ops
)) < 0) {
386 snd_usb_audio_free(chip
);
391 strcpy(card
->driver
, "USB-Audio");
392 sprintf(component
, "USB%04x:%04x",
393 USB_ID_VENDOR(chip
->usb_id
), USB_ID_PRODUCT(chip
->usb_id
));
394 snd_component_add(card
, component
);
396 /* retrieve the device string as shortname */
397 if (quirk
&& quirk
->product_name
&& *quirk
->product_name
) {
398 strlcpy(card
->shortname
, quirk
->product_name
, sizeof(card
->shortname
));
400 if (!dev
->descriptor
.iProduct
||
401 usb_string(dev
, dev
->descriptor
.iProduct
,
402 card
->shortname
, sizeof(card
->shortname
)) <= 0) {
403 /* no name available from anywhere, so use ID */
404 sprintf(card
->shortname
, "USB Device %#04x:%#04x",
405 USB_ID_VENDOR(chip
->usb_id
),
406 USB_ID_PRODUCT(chip
->usb_id
));
409 strim(card
->shortname
);
411 /* retrieve the vendor and device strings as longname */
412 if (quirk
&& quirk
->vendor_name
&& *quirk
->vendor_name
) {
413 len
= strlcpy(card
->longname
, quirk
->vendor_name
, sizeof(card
->longname
));
415 if (dev
->descriptor
.iManufacturer
)
416 len
= usb_string(dev
, dev
->descriptor
.iManufacturer
,
417 card
->longname
, sizeof(card
->longname
));
420 /* we don't really care if there isn't any vendor string */
423 strim(card
->longname
);
425 strlcat(card
->longname
, " ", sizeof(card
->longname
));
428 strlcat(card
->longname
, card
->shortname
, sizeof(card
->longname
));
430 len
= strlcat(card
->longname
, " at ", sizeof(card
->longname
));
432 if (len
< sizeof(card
->longname
))
433 usb_make_path(dev
, card
->longname
+ len
, sizeof(card
->longname
) - len
);
435 switch (snd_usb_get_speed(dev
)) {
437 strlcat(card
->longname
, ", low speed", sizeof(card
->longname
));
440 strlcat(card
->longname
, ", full speed", sizeof(card
->longname
));
443 strlcat(card
->longname
, ", high speed", sizeof(card
->longname
));
445 case USB_SPEED_SUPER
:
446 strlcat(card
->longname
, ", super speed", sizeof(card
->longname
));
452 snd_usb_audio_create_proc(chip
);
459 * probe the active usb device
461 * note that this can be called multiple times per a device, when it
462 * includes multiple audio control interfaces.
464 * thus we check the usb device pointer and creates the card instance
465 * only at the first time. the successive calls of this function will
466 * append the pcm interface to the corresponding card.
468 static int usb_audio_probe(struct usb_interface
*intf
,
469 const struct usb_device_id
*usb_id
)
471 struct usb_device
*dev
= interface_to_usbdev(intf
);
472 const struct snd_usb_audio_quirk
*quirk
=
473 (const struct snd_usb_audio_quirk
*)usb_id
->driver_info
;
474 struct snd_usb_audio
*chip
;
476 struct usb_host_interface
*alts
;
480 alts
= &intf
->altsetting
[0];
481 ifnum
= get_iface_desc(alts
)->bInterfaceNumber
;
482 id
= USB_ID(le16_to_cpu(dev
->descriptor
.idVendor
),
483 le16_to_cpu(dev
->descriptor
.idProduct
));
484 if (quirk
&& quirk
->ifnum
>= 0 && ifnum
!= quirk
->ifnum
)
487 err
= snd_usb_apply_boot_quirk(dev
, intf
, quirk
);
492 * found a config. now register to ALSA
495 /* check whether it's already registered */
497 mutex_lock(®ister_mutex
);
498 for (i
= 0; i
< SNDRV_CARDS
; i
++) {
499 if (usb_chip
[i
] && usb_chip
[i
]->dev
== dev
) {
500 if (atomic_read(&usb_chip
[i
]->shutdown
)) {
501 dev_err(&dev
->dev
, "USB device is in the shutdown state, cannot create a card instance\n");
506 atomic_inc(&chip
->active
); /* avoid autopm */
512 * now look for an empty slot and create a new card instance
514 for (i
= 0; i
< SNDRV_CARDS
; i
++)
515 if (enable
[i
] && ! usb_chip
[i
] &&
516 (vid
[i
] == -1 || vid
[i
] == USB_ID_VENDOR(id
)) &&
517 (pid
[i
] == -1 || pid
[i
] == USB_ID_PRODUCT(id
))) {
518 err
= snd_usb_audio_create(intf
, dev
, i
, quirk
,
522 chip
->pm_intf
= intf
;
526 dev_err(&dev
->dev
, "no available usb audio device\n");
533 * For devices with more than one control interface, we assume the
534 * first contains the audio controls. We might need a more specific
535 * check here in the future.
537 if (!chip
->ctrl_intf
)
538 chip
->ctrl_intf
= alts
;
540 chip
->txfr_quirk
= 0;
541 err
= 1; /* continue */
542 if (quirk
&& quirk
->ifnum
!= QUIRK_NO_INTERFACE
) {
543 /* need some special handlings */
544 err
= snd_usb_create_quirk(chip
, intf
, &usb_audio_driver
, quirk
);
550 /* create normal USB audio interfaces */
551 err
= snd_usb_create_streams(chip
, ifnum
);
554 err
= snd_usb_create_mixer(chip
, ifnum
, ignore_ctl_error
);
559 /* we are allowed to call snd_card_register() many times */
560 err
= snd_card_register(chip
->card
);
564 usb_chip
[chip
->index
] = chip
;
565 chip
->num_interfaces
++;
566 usb_set_intfdata(intf
, chip
);
567 atomic_dec(&chip
->active
);
568 mutex_unlock(®ister_mutex
);
573 if (!chip
->num_interfaces
)
574 snd_card_free(chip
->card
);
575 atomic_dec(&chip
->active
);
577 mutex_unlock(®ister_mutex
);
582 * we need to take care of counter, since disconnection can be called also
583 * many times as well as usb_audio_probe().
585 static void usb_audio_disconnect(struct usb_interface
*intf
)
587 struct snd_usb_audio
*chip
= usb_get_intfdata(intf
);
588 struct snd_card
*card
;
591 if (chip
== (void *)-1L)
596 mutex_lock(®ister_mutex
);
597 if (atomic_inc_return(&chip
->shutdown
) == 1) {
598 struct snd_usb_stream
*as
;
599 struct snd_usb_endpoint
*ep
;
600 struct usb_mixer_interface
*mixer
;
602 /* wait until all pending tasks done;
603 * they are protected by snd_usb_lock_shutdown()
605 wait_event(chip
->shutdown_wait
,
606 !atomic_read(&chip
->usage_count
));
607 snd_card_disconnect(card
);
608 /* release the pcm resources */
609 list_for_each_entry(as
, &chip
->pcm_list
, list
) {
610 snd_usb_stream_disconnect(as
);
612 /* release the endpoint resources */
613 list_for_each_entry(ep
, &chip
->ep_list
, list
) {
614 snd_usb_endpoint_release(ep
);
616 /* release the midi resources */
617 list_for_each(p
, &chip
->midi_list
) {
618 snd_usbmidi_disconnect(p
);
620 /* release mixer resources */
621 list_for_each_entry(mixer
, &chip
->mixer_list
, list
) {
622 snd_usb_mixer_disconnect(mixer
);
626 chip
->num_interfaces
--;
627 if (chip
->num_interfaces
<= 0) {
628 usb_chip
[chip
->index
] = NULL
;
629 mutex_unlock(®ister_mutex
);
630 snd_card_free_when_closed(card
);
632 mutex_unlock(®ister_mutex
);
636 /* lock the shutdown (disconnect) task and autoresume */
637 int snd_usb_lock_shutdown(struct snd_usb_audio
*chip
)
641 atomic_inc(&chip
->usage_count
);
642 if (atomic_read(&chip
->shutdown
)) {
646 err
= snd_usb_autoresume(chip
);
652 if (atomic_dec_and_test(&chip
->usage_count
))
653 wake_up(&chip
->shutdown_wait
);
657 /* autosuspend and unlock the shutdown */
658 void snd_usb_unlock_shutdown(struct snd_usb_audio
*chip
)
660 snd_usb_autosuspend(chip
);
661 if (atomic_dec_and_test(&chip
->usage_count
))
662 wake_up(&chip
->shutdown_wait
);
667 int snd_usb_autoresume(struct snd_usb_audio
*chip
)
669 if (atomic_read(&chip
->shutdown
))
671 if (atomic_inc_return(&chip
->active
) == 1)
672 return usb_autopm_get_interface(chip
->pm_intf
);
676 void snd_usb_autosuspend(struct snd_usb_audio
*chip
)
678 if (atomic_dec_and_test(&chip
->active
))
679 usb_autopm_put_interface(chip
->pm_intf
);
682 static int usb_audio_suspend(struct usb_interface
*intf
, pm_message_t message
)
684 struct snd_usb_audio
*chip
= usb_get_intfdata(intf
);
685 struct snd_usb_stream
*as
;
686 struct usb_mixer_interface
*mixer
;
689 if (chip
== (void *)-1L)
692 chip
->autosuspended
= !!PMSG_IS_AUTO(message
);
693 if (!chip
->autosuspended
)
694 snd_power_change_state(chip
->card
, SNDRV_CTL_POWER_D3hot
);
695 if (!chip
->num_suspended_intf
++) {
696 list_for_each_entry(as
, &chip
->pcm_list
, list
) {
697 snd_pcm_suspend_all(as
->pcm
);
698 as
->substream
[0].need_setup_ep
=
699 as
->substream
[1].need_setup_ep
= true;
701 list_for_each(p
, &chip
->midi_list
)
702 snd_usbmidi_suspend(p
);
703 list_for_each_entry(mixer
, &chip
->mixer_list
, list
)
704 snd_usb_mixer_suspend(mixer
);
710 static int __usb_audio_resume(struct usb_interface
*intf
, bool reset_resume
)
712 struct snd_usb_audio
*chip
= usb_get_intfdata(intf
);
713 struct usb_mixer_interface
*mixer
;
717 if (chip
== (void *)-1L)
719 if (--chip
->num_suspended_intf
)
722 atomic_inc(&chip
->active
); /* avoid autopm */
724 * ALSA leaves material resumption to user space
725 * we just notify and restart the mixers
727 list_for_each_entry(mixer
, &chip
->mixer_list
, list
) {
728 err
= snd_usb_mixer_resume(mixer
, reset_resume
);
733 list_for_each(p
, &chip
->midi_list
) {
734 snd_usbmidi_resume(p
);
737 if (!chip
->autosuspended
)
738 snd_power_change_state(chip
->card
, SNDRV_CTL_POWER_D0
);
739 chip
->autosuspended
= 0;
742 atomic_dec(&chip
->active
); /* allow autopm after this point */
746 static int usb_audio_resume(struct usb_interface
*intf
)
748 return __usb_audio_resume(intf
, false);
751 static int usb_audio_reset_resume(struct usb_interface
*intf
)
753 return __usb_audio_resume(intf
, true);
756 #define usb_audio_suspend NULL
757 #define usb_audio_resume NULL
758 #define usb_audio_reset_resume NULL
759 #endif /* CONFIG_PM */
761 static struct usb_device_id usb_audio_ids
[] = {
762 #include "quirks-table.h"
763 { .match_flags
= (USB_DEVICE_ID_MATCH_INT_CLASS
| USB_DEVICE_ID_MATCH_INT_SUBCLASS
),
764 .bInterfaceClass
= USB_CLASS_AUDIO
,
765 .bInterfaceSubClass
= USB_SUBCLASS_AUDIOCONTROL
},
766 { } /* Terminating entry */
768 MODULE_DEVICE_TABLE(usb
, usb_audio_ids
);
771 * entry point for linux usb interface
774 static struct usb_driver usb_audio_driver
= {
775 .name
= "snd-usb-audio",
776 .probe
= usb_audio_probe
,
777 .disconnect
= usb_audio_disconnect
,
778 .suspend
= usb_audio_suspend
,
779 .resume
= usb_audio_resume
,
780 .reset_resume
= usb_audio_reset_resume
,
781 .id_table
= usb_audio_ids
,
782 .supports_autosuspend
= 1,
785 module_usb_driver(usb_audio_driver
);