Re: [PATCH 2/2] usbtv: add audio support

[Mauro Carvalho Chehab <m.chehab@samsung.com>]

Em Tue,  7 Jan 2014 23:13:22 +0100
Federico Simoncelli <federico.simoncelli@gmail.com> escreveu:

> From: Federico Simoncelli <fsimonce@redhat.com>
> 
> Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
> Tested-by: Lubomir Rintel <lkundrak@v3.sk>
> ---
>  drivers/media/usb/usbtv/Makefile      |   3 +-
>  drivers/media/usb/usbtv/usbtv-audio.c | 384 ++++++++++++++++++++++++++++++++++
>  drivers/media/usb/usbtv/usbtv-core.c  |  16 +-
>  drivers/media/usb/usbtv/usbtv-video.c |   9 +-
>  drivers/media/usb/usbtv/usbtv.h       |  21 +-
>  5 files changed, 423 insertions(+), 10 deletions(-)
>  create mode 100644 drivers/media/usb/usbtv/usbtv-audio.c
> 
> diff --git a/drivers/media/usb/usbtv/Makefile b/drivers/media/usb/usbtv/Makefile
> index 775316a..f555cf8 100644
> --- a/drivers/media/usb/usbtv/Makefile
> +++ b/drivers/media/usb/usbtv/Makefile
> @@ -1,4 +1,5 @@
>  usbtv-y := usbtv-core.o \
> -	usbtv-video.o
> +	usbtv-video.o \
> +	usbtv-audio.o
>  
>  obj-$(CONFIG_VIDEO_USBTV) += usbtv.o
> diff --git a/drivers/media/usb/usbtv/usbtv-audio.c b/drivers/media/usb/usbtv/usbtv-audio.c
> new file mode 100644
> index 0000000..3acc52c
> --- /dev/null
> +++ b/drivers/media/usb/usbtv/usbtv-audio.c
> @@ -0,0 +1,384 @@
> +/*
> + * Fushicai USBTV007 Audio-Video Grabber Driver
> + *
> + * Product web site:
> + * http://www.fushicai.com/products_detail/&productId=d05449ee-b690-42f9-a661-aa7353894bed.html
> + *
> + * Copyright (c) 2013 Federico Simoncelli
> + * All rights reserved.
> + * No physical hardware was harmed running Windows during the
> + * reverse-engineering activity
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + *    notice, this list of conditions, and the following disclaimer,
> + *    without modification.
> + * 2. The name of the author may not be used to endorse or promote products
> + *    derived from this software without specific prior written permission.
> + *
> + * Alternatively, this software may be distributed under the terms of the
> + * GNU General Public License ("GPL").
> + */
> +
> +#include <sound/core.h>
> +#include <sound/initval.h>
> +#include <sound/ac97_codec.h>
> +#include <sound/pcm_params.h>
> +
> +#include "usbtv.h"
> +
> +static struct snd_pcm_hardware snd_usbtv_digital_hw = {
> +	.info = SNDRV_PCM_INFO_BATCH |
> +		SNDRV_PCM_INFO_MMAP |
> +		SNDRV_PCM_INFO_INTERLEAVED |
> +		SNDRV_PCM_INFO_BLOCK_TRANSFER |
> +		SNDRV_PCM_INFO_MMAP_VALID,
> +	.formats = SNDRV_PCM_FMTBIT_S16_LE,
> +	.rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_KNOT,

No, the above is wrong. It should be, instead:

	.rates = SNDRV_PCM_RATE_48000,

> +	.rate_min = 48000,
> +	.rate_max = 48000,
> +	.channels_min = 2,
> +	.channels_max = 2,

> +	.period_bytes_min = 64,
> +	.period_bytes_max = 12544,

The above is likely wrong too, as it seems that you're using a fixed
number of URBs and a fixed URB size.

An invalid period size can cause bad audio artifacts. Basically, you need
to estimate/check how many URBs you're receiving per second, and what's
their size, in order to fill these.

I did such review on one of the drivers, at:
	http://git.linuxtv.org/mchehab/experimental.git/shortlog/refs/heads/em28xx

In particular, I suggest you to take a look on those patches:
	http://git.linuxtv.org/mchehab/experimental.git/commitdiff/1b3fd2d342667005855deae74200195695433259
	http://git.linuxtv.org/mchehab/experimental.git/commitdiff/49677aef90de7834e7bb4b0adf95c3342c2c8668
	http://git.linuxtv.org/mchehab/experimental.git/commitdiff/a02b9c238b408f69fc78d528b549b85001df98b8

As it provides a way to dynamically fill it in runtime, showing the
calculus to estimate those values.

> +	.periods_min = 2,
> +	.periods_max = 98,
> +	.buffer_bytes_max = 62720 * 8, /* value in usbaudio.c */
> +};
> +
> +static int snd_usbtv_pcm_open(struct snd_pcm_substream *substream)
> +{
> +	struct usbtv *chip = snd_pcm_substream_chip(substream);
> +	struct snd_pcm_runtime *runtime = substream->runtime;
> +
> +	chip->snd_substream = substream;
> +	runtime->hw = snd_usbtv_digital_hw;
> +
> +	return 0;
> +}
> +
> +static int snd_usbtv_pcm_close(struct snd_pcm_substream *substream)
> +{
> +	struct usbtv *chip = snd_pcm_substream_chip(substream);
> +
> +	if (atomic_read(&chip->snd_stream)) {
> +		atomic_set(&chip->snd_stream, 0);
> +		schedule_work(&chip->snd_trigger);
> +	}
> +
> +	return 0;
> +}
> +
> +static int snd_usbtv_hw_params(struct snd_pcm_substream *substream,
> +		struct snd_pcm_hw_params *hw_params)
> +{
> +	int rv;
> +	struct usbtv *chip = snd_pcm_substream_chip(substream);
> +
> +	rv = snd_pcm_lib_malloc_pages(substream,
> +		params_buffer_bytes(hw_params));
> +
> +	if (rv < 0) {
> +		dev_warn(chip->dev, "pcm audio buffer allocation failure %i\n",
> +			rv);
> +		return rv;
> +	}
> +
> +	return 0;
> +}
> +
> +static int snd_usbtv_hw_free(struct snd_pcm_substream *substream)
> +{
> +	snd_pcm_lib_free_pages(substream);
> +	return 0;
> +}
> +
> +static int snd_usbtv_prepare(struct snd_pcm_substream *substream)
> +{
> +	struct usbtv *chip = snd_pcm_substream_chip(substream);
> +
> +	chip->snd_buffer_pos = 0;
> +	chip->snd_period_pos = 0;
> +
> +	return 0;
> +}
> +
> +static void usbtv_audio_urb_received(struct urb *urb)
> +{
> +	struct usbtv *chip = urb->context;
> +	struct snd_pcm_substream *substream = chip->snd_substream;
> +	struct snd_pcm_runtime *runtime = substream->runtime;
> +	size_t i, frame_bytes, chunk_length, buffer_pos, period_pos;
> +	int period_elapsed;
> +	void *urb_current;
> +
> +	switch (urb->status) {
> +	case 0:
> +	case -ETIMEDOUT:
> +		break;
> +	case -ENOENT:
> +	case -EPROTO:
> +	case -ECONNRESET:
> +	case -ESHUTDOWN:
> +		return;
> +	default:
> +		dev_warn(chip->dev, "unknown audio urb status %i\n",
> +			urb->status);
> +	}
> +
> +	if (!atomic_read(&chip->snd_stream))
> +		return;
> +
> +	frame_bytes = runtime->frame_bits >> 3;
> +	chunk_length = USBTV_CHUNK / frame_bytes;
> +
> +	buffer_pos = chip->snd_buffer_pos;
> +	period_pos = chip->snd_period_pos;
> +	period_elapsed = 0;
> +
> +	for (i = 0; i < urb->actual_length; i += USBTV_CHUNK_SIZE) {
> +		urb_current = urb->transfer_buffer + i + USBTV_AUDIO_HDRSIZE;
> +
> +		if (buffer_pos + chunk_length >= runtime->buffer_size) {
> +			size_t cnt = (runtime->buffer_size - buffer_pos) *
> +				frame_bytes;
> +			memcpy(runtime->dma_area + buffer_pos * frame_bytes,
> +				urb_current, cnt);
> +			memcpy(runtime->dma_area, urb_current + cnt,
> +				chunk_length * frame_bytes - cnt);
> +		} else {
> +			memcpy(runtime->dma_area + buffer_pos * frame_bytes,
> +				urb_current, chunk_length * frame_bytes);
> +		}
> +
> +		buffer_pos += chunk_length;
> +		period_pos += chunk_length;
> +
> +		if (buffer_pos >= runtime->buffer_size)
> +			buffer_pos -= runtime->buffer_size;
> +
> +		if (period_pos >= runtime->period_size) {
> +			period_pos -= runtime->period_size;
> +			period_elapsed = 1;
> +		}
> +	}
> +
> +	snd_pcm_stream_lock(substream);
> +
> +	chip->snd_buffer_pos = buffer_pos;
> +	chip->snd_period_pos = period_pos;
> +
> +	snd_pcm_stream_unlock(substream);
> +
> +	if (period_elapsed)
> +		snd_pcm_period_elapsed(substream);
> +
> +	usb_submit_urb(urb, GFP_ATOMIC);
> +}
> +
> +static int usbtv_audio_start(struct usbtv *chip)
> +{
> +	unsigned int pipe;
> +	static const u16 setup[][2] = {
> +		/* These seem to enable the device. */
> +		{ USBTV_BASE + 0x0008, 0x0001 },
> +		{ USBTV_BASE + 0x01d0, 0x00ff },
> +		{ USBTV_BASE + 0x01d9, 0x0002 },
> +
> +		{ USBTV_BASE + 0x01da, 0x0013 },
> +		{ USBTV_BASE + 0x01db, 0x0012 },
> +		{ USBTV_BASE + 0x01e9, 0x0002 },
> +		{ USBTV_BASE + 0x01ec, 0x006c },
> +		{ USBTV_BASE + 0x0294, 0x0020 },
> +		{ USBTV_BASE + 0x0255, 0x00cf },
> +		{ USBTV_BASE + 0x0256, 0x0020 },
> +		{ USBTV_BASE + 0x01eb, 0x0030 },
> +		{ USBTV_BASE + 0x027d, 0x00a6 },
> +		{ USBTV_BASE + 0x0280, 0x0011 },
> +		{ USBTV_BASE + 0x0281, 0x0040 },
> +		{ USBTV_BASE + 0x0282, 0x0011 },
> +		{ USBTV_BASE + 0x0283, 0x0040 },
> +		{ 0xf891, 0x0010 },
> +
> +		/* this sets the input from composite */
> +		{ USBTV_BASE + 0x0284, 0x00aa },
> +	};
> +
> +	chip->snd_bulk_urb = usb_alloc_urb(0, GFP_KERNEL);
> +	if (chip->snd_bulk_urb == NULL)
> +		goto err_alloc_urb;
> +
> +	pipe = usb_rcvbulkpipe(chip->udev, USBTV_AUDIO_ENDP);
> +
> +	chip->snd_bulk_urb->transfer_buffer = kzalloc(
> +		USBTV_AUDIO_URBSIZE, GFP_KERNEL);
> +	if (chip->snd_bulk_urb->transfer_buffer == NULL)
> +		goto err_transfer_buffer;
> +
> +	usb_fill_bulk_urb(chip->snd_bulk_urb, chip->udev, pipe,
> +		chip->snd_bulk_urb->transfer_buffer, USBTV_AUDIO_URBSIZE,
> +		usbtv_audio_urb_received, chip);
> +
> +	/* starting the stream */
> +	usbtv_set_regs(chip, setup, ARRAY_SIZE(setup));
> +
> +	usb_clear_halt(chip->udev, pipe);
> +	usb_submit_urb(chip->snd_bulk_urb, GFP_ATOMIC);
> +
> +	return 0;
> +
> +err_transfer_buffer:
> +	usb_free_urb(chip->snd_bulk_urb);
> +	chip->snd_bulk_urb = NULL;
> +
> +err_alloc_urb:
> +	return -ENOMEM;
> +}
> +
> +static int usbtv_audio_stop(struct usbtv *chip)
> +{
> +	static const u16 setup[][2] = {
> +	/* The original windows driver sometimes sends also:
> +	 *   { USBTV_BASE + 0x00a2, 0x0013 }
> +	 * but it seems useless and its real effects are untested at
> +	 * the moment.
> +	 */
> +		{ USBTV_BASE + 0x027d, 0x0000 },
> +		{ USBTV_BASE + 0x0280, 0x0010 },
> +		{ USBTV_BASE + 0x0282, 0x0010 },
> +	};
> +
> +	if (chip->snd_bulk_urb) {
> +		usb_kill_urb(chip->snd_bulk_urb);
> +		kfree(chip->snd_bulk_urb->transfer_buffer);
> +		usb_free_urb(chip->snd_bulk_urb);
> +		chip->snd_bulk_urb = NULL;
> +	}
> +
> +	usbtv_set_regs(chip, setup, ARRAY_SIZE(setup));
> +
> +	return 0;
> +}
> +
> +void usbtv_audio_suspend(struct usbtv *usbtv)
> +{
> +	if (atomic_read(&usbtv->snd_stream) && usbtv->snd_bulk_urb)
> +		usb_kill_urb(usbtv->snd_bulk_urb);
> +}
> +
> +void usbtv_audio_resume(struct usbtv *usbtv)
> +{
> +	if (atomic_read(&usbtv->snd_stream) && usbtv->snd_bulk_urb)
> +		usb_submit_urb(usbtv->snd_bulk_urb, GFP_ATOMIC);
> +}
> +
> +static void snd_usbtv_trigger(struct work_struct *work)
> +{
> +	struct usbtv *chip = container_of(work, struct usbtv, snd_trigger);
> +
> +	if (atomic_read(&chip->snd_stream))
> +		usbtv_audio_start(chip);
> +	else
> +		usbtv_audio_stop(chip);
> +}
> +
> +static int snd_usbtv_card_trigger(struct snd_pcm_substream *substream, int cmd)
> +{
> +	struct usbtv *chip = snd_pcm_substream_chip(substream);
> +
> +	switch (cmd) {
> +	case SNDRV_PCM_TRIGGER_START:
> +	case SNDRV_PCM_TRIGGER_RESUME:
> +	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
> +		atomic_set(&chip->snd_stream, 1);
> +		break;
> +	case SNDRV_PCM_TRIGGER_STOP:
> +	case SNDRV_PCM_TRIGGER_SUSPEND:
> +	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
> +		atomic_set(&chip->snd_stream, 0);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	schedule_work(&chip->snd_trigger);
> +
> +	return 0;
> +}
> +
> +static snd_pcm_uframes_t snd_usbtv_pointer(struct snd_pcm_substream *substream)
> +{
> +	struct usbtv *chip = snd_pcm_substream_chip(substream);
> +	return chip->snd_buffer_pos;
> +}
> +
> +static struct snd_pcm_ops snd_usbtv_pcm_ops = {
> +	.open = snd_usbtv_pcm_open,
> +	.close = snd_usbtv_pcm_close,
> +	.ioctl = snd_pcm_lib_ioctl,
> +	.hw_params = snd_usbtv_hw_params,
> +	.hw_free = snd_usbtv_hw_free,
> +	.prepare = snd_usbtv_prepare,
> +	.trigger = snd_usbtv_card_trigger,
> +	.pointer = snd_usbtv_pointer,
> +};
> +
> +int usbtv_audio_init(struct usbtv *usbtv)
> +{
> +	int rv;
> +	struct snd_card *card;
> +	struct snd_pcm *pcm;
> +
> +	INIT_WORK(&usbtv->snd_trigger, snd_usbtv_trigger);
> +	atomic_set(&usbtv->snd_stream, 0);
> +
> +	rv = snd_card_create(SNDRV_DEFAULT_IDX1, "usbtv", THIS_MODULE, 0,
> +		&card);
> +	if (rv < 0)
> +		return rv;
> +
> +	strlcpy(card->driver, usbtv->dev->driver->name, sizeof(card->driver));
> +	strlcpy(card->shortname, "usbtv", sizeof(card->shortname));
> +	snprintf(card->longname, sizeof(card->longname),
> +		"USBTV Audio at bus %d device %d", usbtv->udev->bus->busnum,
> +		usbtv->udev->devnum);
> +
> +	snd_card_set_dev(card, usbtv->dev);
> +
> +	usbtv->snd = card;
> +
> +	rv = snd_pcm_new(card, "USBTV Audio", 0, 0, 1, &pcm);
> +	if (rv < 0)
> +		goto err;
> +
> +	strlcpy(pcm->name, "USBTV Audio Input", sizeof(pcm->name));
> +	pcm->info_flags = 0;
> +	pcm->private_data = usbtv;
> +
> +	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_usbtv_pcm_ops);
> +	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
> +		snd_dma_continuous_data(GFP_KERNEL), USBTV_AUDIO_BUFFER,
> +		USBTV_AUDIO_BUFFER);
> +
> +	rv = snd_card_register(card);
> +	if (rv)
> +		goto err;
> +
> +	return 0;
> +
> +err:
> +	usbtv->snd = NULL;
> +	snd_card_free(card);
> +
> +	return rv;
> +}
> +
> +void usbtv_audio_free(struct usbtv *usbtv)
> +{
> +	if (usbtv->snd && usbtv->udev) {
> +		snd_card_free(usbtv->snd);
> +		usbtv->snd = NULL;
> +	}
> +}
> diff --git a/drivers/media/usb/usbtv/usbtv-core.c b/drivers/media/usb/usbtv/usbtv-core.c
> index e89e48b..bdc920c 100644
> --- a/drivers/media/usb/usbtv/usbtv-core.c
> +++ b/drivers/media/usb/usbtv/usbtv-core.c
> @@ -1,5 +1,5 @@
>  /*
> - * Fushicai USBTV007 Video Grabber Driver
> + * Fushicai USBTV007 Audio-Video Grabber Driver
>   *
>   * Product web site:
>   * http://www.fushicai.com/products_detail/&productId=d05449ee-b690-42f9-a661-aa7353894bed.html
> @@ -86,12 +86,19 @@ static int usbtv_probe(struct usb_interface *intf,
>  	if (ret < 0)
>  		goto usbtv_video_fail;
>  
> +	ret = usbtv_audio_init(usbtv);
> +	if (ret < 0)
> +		goto usbtv_audio_fail;
> +
>  	/* for simplicity we exploit the v4l2_device reference counting */
>  	v4l2_device_get(&usbtv->v4l2_dev);
>  
> -	dev_info(dev, "Fushicai USBTV007 Video Grabber\n");
> +	dev_info(dev, "Fushicai USBTV007 Audio-Video Grabber\n");
>  	return 0;
>  
> +usbtv_audio_fail:
> +	usbtv_video_free(usbtv);
> +
>  usbtv_video_fail:
>  	kfree(usbtv);
>  
> @@ -106,6 +113,7 @@ static void usbtv_disconnect(struct usb_interface *intf)
>  	if (!usbtv)
>  		return;
>  
> +	usbtv_audio_free(usbtv);
>  	usbtv_video_free(usbtv);
>  
>  	usb_put_dev(usbtv->udev);
> @@ -122,8 +130,8 @@ struct usb_device_id usbtv_id_table[] = {
>  };
>  MODULE_DEVICE_TABLE(usb, usbtv_id_table);
>  
> -MODULE_AUTHOR("Lubomir Rintel");
> -MODULE_DESCRIPTION("Fushicai USBTV007 Video Grabber Driver");
> +MODULE_AUTHOR("Lubomir Rintel, Federico Simoncelli");
> +MODULE_DESCRIPTION("Fushicai USBTV007 Audio-Video Grabber Driver");
>  MODULE_LICENSE("Dual BSD/GPL");
>  
>  struct usb_driver usbtv_usb_driver = {
> diff --git a/drivers/media/usb/usbtv/usbtv-video.c b/drivers/media/usb/usbtv/usbtv-video.c
> index 496bc2e..da604fa 100644
> --- a/drivers/media/usb/usbtv/usbtv-video.c
> +++ b/drivers/media/usb/usbtv/usbtv-video.c
> @@ -1,5 +1,5 @@
>  /*
> - * Fushicai USBTV007 Video Grabber Driver
> + * Fushicai USBTV007 Audio-Video Grabber Driver
>   *
>   * Product web site:
>   * http://www.fushicai.com/products_detail/&productId=d05449ee-b690-42f9-a661-aa7353894bed.html
> @@ -79,7 +79,6 @@ static int usbtv_select_input(struct usbtv *usbtv, int input)
>  		{ USBTV_BASE + 0x011f, 0x00f2 },
>  		{ USBTV_BASE + 0x0127, 0x0060 },
>  		{ USBTV_BASE + 0x00ae, 0x0010 },
> -		{ USBTV_BASE + 0x0284, 0x00aa },
>  		{ USBTV_BASE + 0x0239, 0x0060 },
>  	};
>  
> @@ -88,7 +87,6 @@ static int usbtv_select_input(struct usbtv *usbtv, int input)
>  		{ USBTV_BASE + 0x011f, 0x00ff },
>  		{ USBTV_BASE + 0x0127, 0x0060 },
>  		{ USBTV_BASE + 0x00ae, 0x0030 },
> -		{ USBTV_BASE + 0x0284, 0x0088 },
>  		{ USBTV_BASE + 0x0239, 0x0060 },
>  	};
>  
> @@ -225,7 +223,6 @@ static int usbtv_setup_capture(struct usbtv *usbtv)
>  		{ USBTV_BASE + 0x0159, 0x0006 },
>  		{ USBTV_BASE + 0x015d, 0x0000 },
>  
> -		{ USBTV_BASE + 0x0284, 0x0088 },
>  		{ USBTV_BASE + 0x0003, 0x0004 },
>  		{ USBTV_BASE + 0x0100, 0x00d3 },
>  		{ USBTV_BASE + 0x0115, 0x0015 },
> @@ -434,6 +431,8 @@ static int usbtv_start(struct usbtv *usbtv)
>  	int i;
>  	int ret;
>  
> +	usbtv_audio_suspend(usbtv);
> +
>  	ret = usb_set_interface(usbtv->udev, 0, 0);
>  	if (ret < 0)
>  		return ret;
> @@ -446,6 +445,8 @@ static int usbtv_start(struct usbtv *usbtv)
>  	if (ret < 0)
>  		return ret;
>  
> +	usbtv_audio_resume(usbtv);
> +
>  	for (i = 0; i < USBTV_ISOC_TRANSFERS; i++) {
>  		struct urb *ip;
>  
> diff --git a/drivers/media/usb/usbtv/usbtv.h b/drivers/media/usb/usbtv/usbtv.h
> index 536343d..8cb69ea 100644
> --- a/drivers/media/usb/usbtv/usbtv.h
> +++ b/drivers/media/usb/usbtv/usbtv.h
> @@ -1,5 +1,5 @@
>  /*
> - * Fushicai USBTV007 Video Grabber Driver
> + * Fushicai USBTV007 Audio-Video Grabber Driver
>   *
>   * Copyright (c) 2013 Lubomir Rintel
>   * All rights reserved.
> @@ -27,6 +27,7 @@
>  
>  /* Hardware. */
>  #define USBTV_VIDEO_ENDP	0x81
> +#define USBTV_AUDIO_ENDP	0x83
>  #define USBTV_BASE		0xc000
>  #define USBTV_REQUEST_REG	12
>  
> @@ -38,6 +39,10 @@
>  #define USBTV_CHUNK_SIZE	256
>  #define USBTV_CHUNK		240
>  
> +#define USBTV_AUDIO_URBSIZE	20480
> +#define USBTV_AUDIO_HDRSIZE	4
> +#define USBTV_AUDIO_BUFFER	65536
> +
>  /* Chunk header. */
>  #define USBTV_MAGIC_OK(chunk)	((be32_to_cpu(chunk[0]) & 0xff000000) \
>  							== 0x88000000)
> @@ -90,9 +95,23 @@ struct usbtv {
>  	int iso_size;
>  	unsigned int sequence;
>  	struct urb *isoc_urbs[USBTV_ISOC_TRANSFERS];
> +
> +	/* audio */
> +	struct snd_card *snd;
> +	struct snd_pcm_substream *snd_substream;
> +	atomic_t snd_stream;
> +	struct work_struct snd_trigger;
> +	struct urb *snd_bulk_urb;
> +	size_t snd_buffer_pos;
> +	size_t snd_period_pos;
>  };
>  
>  int usbtv_set_regs(struct usbtv *usbtv, const u16 regs[][2], int size);
>  
>  int usbtv_video_init(struct usbtv *usbtv);
>  void usbtv_video_free(struct usbtv *usbtv);
> +
> +int usbtv_audio_init(struct usbtv *usbtv);
> +void usbtv_audio_free(struct usbtv *usbtv);
> +void usbtv_audio_suspend(struct usbtv *usbtv);
> +void usbtv_audio_resume(struct usbtv *usbtv);


-- 

Cheers,
Mauro