ALSA: usb-audio: refactor code

Clean up the usb audio driver by factoring out a lot of functions to
separate files. Code for procfs, quirks, urbs, format parsers etc all
got a new home now.

Moved almost all special quirk handling to quirks.c and introduced new
generic functions to handle them, so the exceptions do not pollute the
whole driver.

Renamed usbaudio.c to card.c because this is what it actually does now.
Renamed usbmidi.c to midi.c for namespace clarity.
Removed more things from usbaudio.h.

The non-standard drivers were adopted accordingly.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 592 insertions, 0 deletions

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
new file mode 100644
index 000000000000..4c16920844ea
--- /dev/null
+++ b/sound/usb/quirks.c
@@ -0,0 +1,592 @@
+/*
+ *   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/usb.h>
+#include <linux/usb/audio.h>
+
+#include <sound/core.h>
+#include <sound/info.h>
+#include <sound/pcm.h>
+
+#include "usbaudio.h"
+#include "card.h"
+#include "usbmixer.h"
+#include "midi.h"
+#include "quirks.h"
+#include "helper.h"
+#include "endpoint.h"
+#include "pcm.h"
+
+/*
+ * handle the quirks for the contained interfaces
+ */
+static int create_composite_quirk(struct snd_usb_audio *chip,
+				  struct usb_interface *iface,
+				  struct usb_driver *driver,
+				  const struct snd_usb_audio_quirk *quirk)
+{
+	int probed_ifnum = get_iface_desc(iface->altsetting)->bInterfaceNumber;
+	int err;
+
+	for (quirk = quirk->data; quirk->ifnum >= 0; ++quirk) {
+		iface = usb_ifnum_to_if(chip->dev, quirk->ifnum);
+		if (!iface)
+			continue;
+		if (quirk->ifnum != probed_ifnum &&
+		    usb_interface_claimed(iface))
+			continue;
+		err = snd_usb_create_quirk(chip, iface, driver, quirk);
+		if (err < 0)
+			return err;
+		if (quirk->ifnum != probed_ifnum)
+			usb_driver_claim_interface(driver, iface, (void *)-1L);
+	}
+	return 0;
+}
+
+static int ignore_interface_quirk(struct snd_usb_audio *chip,
+				  struct usb_interface *iface,
+				  struct usb_driver *driver,
+				  const struct snd_usb_audio_quirk *quirk)
+{
+	return 0;
+}
+
+
+/*
+ * Allow alignment on audio sub-slot (channel samples) rather than
+ * on audio slots (audio frames)
+ */
+static int create_align_transfer_quirk(struct snd_usb_audio *chip,
+				       struct usb_interface *iface,
+				       struct usb_driver *driver,
+				       const struct snd_usb_audio_quirk *quirk)
+{
+	chip->txfr_quirk = 1;
+	return 1;	/* Continue with creating streams and mixer */
+}
+
+static int create_any_midi_quirk(struct snd_usb_audio *chip,
+				 struct usb_interface *intf,
+				 struct usb_driver *driver,
+				 const struct snd_usb_audio_quirk *quirk)
+{
+	return snd_usbmidi_create(chip->card, intf, &chip->midi_list, quirk);
+}
+
+/*
+ * create a stream for an interface with proper descriptors
+ */
+static int create_standard_audio_quirk(struct snd_usb_audio *chip,
+				       struct usb_interface *iface,
+				       struct usb_driver *driver,
+				       const struct snd_usb_audio_quirk *quirk)
+{
+	struct usb_host_interface *alts;
+	struct usb_interface_descriptor *altsd;
+	int err;
+
+	alts = &iface->altsetting[0];
+	altsd = get_iface_desc(alts);
+	err = snd_usb_parse_audio_endpoints(chip, altsd->bInterfaceNumber);
+	if (err < 0) {
+		snd_printk(KERN_ERR "cannot setup if %d: error %d\n",
+			   altsd->bInterfaceNumber, err);
+		return err;
+	}
+	/* reset the current interface */
+	usb_set_interface(chip->dev, altsd->bInterfaceNumber, 0);
+	return 0;
+}
+
+/*
+ * create a stream for an endpoint/altsetting without proper descriptors
+ */
+static int create_fixed_stream_quirk(struct snd_usb_audio *chip,
+				     struct usb_interface *iface,
+				     struct usb_driver *driver,
+				     const struct snd_usb_audio_quirk *quirk)
+{
+	struct audioformat *fp;
+	struct usb_host_interface *alts;
+	int stream, err;
+	unsigned *rate_table = NULL;
+
+	fp = kmemdup(quirk->data, sizeof(*fp), GFP_KERNEL);
+	if (! fp) {
+		snd_printk(KERN_ERR "cannot memdup\n");
+		return -ENOMEM;
+	}
+	if (fp->nr_rates > 0) {
+		rate_table = kmalloc(sizeof(int) * fp->nr_rates, GFP_KERNEL);
+		if (!rate_table) {
+			kfree(fp);
+			return -ENOMEM;
+		}
+		memcpy(rate_table, fp->rate_table, sizeof(int) * fp->nr_rates);
+		fp->rate_table = rate_table;
+	}
+
+	stream = (fp->endpoint & USB_DIR_IN)
+		? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
+	err = snd_usb_add_audio_endpoint(chip, stream, fp);
+	if (err < 0) {
+		kfree(fp);
+		kfree(rate_table);
+		return err;
+	}
+	if (fp->iface != get_iface_desc(&iface->altsetting[0])->bInterfaceNumber ||
+	    fp->altset_idx >= iface->num_altsetting) {
+		kfree(fp);
+		kfree(rate_table);
+		return -EINVAL;
+	}
+	alts = &iface->altsetting[fp->altset_idx];
+	fp->datainterval = snd_usb_parse_datainterval(chip, alts);
+	fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
+	usb_set_interface(chip->dev, fp->iface, 0);
+	snd_usb_init_pitch(chip->dev, fp->iface, alts, fp);
+	snd_usb_init_sample_rate(chip->dev, fp->iface, alts, fp, fp->rate_max);
+	return 0;
+}
+
+/*
+ * Create a stream for an Edirol UA-700/UA-25/UA-4FX interface.  
+ * The only way to detect the sample rate is by looking at wMaxPacketSize.
+ */
+static int create_uaxx_quirk(struct snd_usb_audio *chip,
+			     struct usb_interface *iface,
+			     struct usb_driver *driver,
+			     const struct snd_usb_audio_quirk *quirk)
+{
+	static const struct audioformat ua_format = {
+		.format = SNDRV_PCM_FORMAT_S24_3LE,
+		.channels = 2,
+		.fmt_type = UAC_FORMAT_TYPE_I,
+		.altsetting = 1,
+		.altset_idx = 1,
+		.rates = SNDRV_PCM_RATE_CONTINUOUS,
+	};
+	struct usb_host_interface *alts;
+	struct usb_interface_descriptor *altsd;
+	struct audioformat *fp;
+	int stream, err;
+
+	/* both PCM and MIDI interfaces have 2 or more altsettings */
+	if (iface->num_altsetting < 2)
+		return -ENXIO;
+	alts = &iface->altsetting[1];
+	altsd = get_iface_desc(alts);
+
+	if (altsd->bNumEndpoints == 2) {
+		static const struct snd_usb_midi_endpoint_info ua700_ep = {
+			.out_cables = 0x0003,
+			.in_cables  = 0x0003
+		};
+		static const struct snd_usb_audio_quirk ua700_quirk = {
+			.type = QUIRK_MIDI_FIXED_ENDPOINT,
+			.data = &ua700_ep
+		};
+		static const struct snd_usb_midi_endpoint_info uaxx_ep = {
+			.out_cables = 0x0001,
+			.in_cables  = 0x0001
+		};
+		static const struct snd_usb_audio_quirk uaxx_quirk = {
+			.type = QUIRK_MIDI_FIXED_ENDPOINT,
+			.data = &uaxx_ep
+		};
+		const struct snd_usb_audio_quirk *quirk =
+			chip->usb_id == USB_ID(0x0582, 0x002b)
+			? &ua700_quirk : &uaxx_quirk;
+		return snd_usbmidi_create(chip->card, iface,
+					  &chip->midi_list, quirk);
+	}
+
+	if (altsd->bNumEndpoints != 1)
+		return -ENXIO;
+
+	fp = kmalloc(sizeof(*fp), GFP_KERNEL);
+	if (!fp)
+		return -ENOMEM;
+	memcpy(fp, &ua_format, sizeof(*fp));
+
+	fp->iface = altsd->bInterfaceNumber;
+	fp->endpoint = get_endpoint(alts, 0)->bEndpointAddress;
+	fp->ep_attr = get_endpoint(alts, 0)->bmAttributes;
+	fp->datainterval = 0;
+	fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
+
+	switch (fp->maxpacksize) {
+	case 0x120:
+		fp->rate_max = fp->rate_min = 44100;
+		break;
+	case 0x138:
+	case 0x140:
+		fp->rate_max = fp->rate_min = 48000;
+		break;
+	case 0x258:
+	case 0x260:
+		fp->rate_max = fp->rate_min = 96000;
+		break;
+	default:
+		snd_printk(KERN_ERR "unknown sample rate\n");
+		kfree(fp);
+		return -ENXIO;
+	}
+
+	stream = (fp->endpoint & USB_DIR_IN)
+		? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
+	err = snd_usb_add_audio_endpoint(chip, stream, fp);
+	if (err < 0) {
+		kfree(fp);
+		return err;
+	}
+	usb_set_interface(chip->dev, fp->iface, 0);
+	return 0;
+}
+
+/*
+ * audio-interface quirks
+ *
+ * returns zero if no standard audio/MIDI parsing is needed.
+ * returns a postive value if standard audio/midi interfaces are parsed
+ * after this.
+ * returns a negative value at error.
+ */
+int snd_usb_create_quirk(struct snd_usb_audio *chip,
+			 struct usb_interface *iface,
+			 struct usb_driver *driver,
+			 const struct snd_usb_audio_quirk *quirk)
+{
+	typedef int (*quirk_func_t)(struct snd_usb_audio *,
+				    struct usb_interface *,
+				    struct usb_driver *,
+				    const struct snd_usb_audio_quirk *);
+	static const quirk_func_t quirk_funcs[] = {
+		[QUIRK_IGNORE_INTERFACE] = ignore_interface_quirk,
+		[QUIRK_COMPOSITE] = create_composite_quirk,
+		[QUIRK_MIDI_STANDARD_INTERFACE] = create_any_midi_quirk,
+		[QUIRK_MIDI_FIXED_ENDPOINT] = create_any_midi_quirk,
+		[QUIRK_MIDI_YAMAHA] = create_any_midi_quirk,
+		[QUIRK_MIDI_MIDIMAN] = create_any_midi_quirk,
+		[QUIRK_MIDI_NOVATION] = create_any_midi_quirk,
+		[QUIRK_MIDI_FASTLANE] = create_any_midi_quirk,
+		[QUIRK_MIDI_EMAGIC] = create_any_midi_quirk,
+		[QUIRK_MIDI_CME] = create_any_midi_quirk,
+		[QUIRK_AUDIO_STANDARD_INTERFACE] = create_standard_audio_quirk,
+		[QUIRK_AUDIO_FIXED_ENDPOINT] = create_fixed_stream_quirk,
+		[QUIRK_AUDIO_EDIROL_UAXX] = create_uaxx_quirk,
+		[QUIRK_AUDIO_ALIGN_TRANSFER] = create_align_transfer_quirk
+	};
+
+	if (quirk->type < QUIRK_TYPE_COUNT) {
+		return quirk_funcs[quirk->type](chip, iface, driver, quirk);
+	} else {
+		snd_printd(KERN_ERR "invalid quirk type %d\n", quirk->type);
+		return -ENXIO;
+	}
+}
+
+/*
+ * boot quirks
+ */
+
+#define EXTIGY_FIRMWARE_SIZE_OLD 794
+#define EXTIGY_FIRMWARE_SIZE_NEW 483
+
+static int snd_usb_extigy_boot_quirk(struct usb_device *dev, struct usb_interface *intf)
+{
+	struct usb_host_config *config = dev->actconfig;
+	int err;
+
+	if (le16_to_cpu(get_cfg_desc(config)->wTotalLength) == EXTIGY_FIRMWARE_SIZE_OLD ||
+	    le16_to_cpu(get_cfg_desc(config)->wTotalLength) == EXTIGY_FIRMWARE_SIZE_NEW) {
+		snd_printdd("sending Extigy boot sequence...\n");
+		/* Send message to force it to reconnect with full interface. */
+		err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev,0),
+				      0x10, 0x43, 0x0001, 0x000a, NULL, 0, 1000);
+		if (err < 0) snd_printdd("error sending boot message: %d\n", err);
+		err = usb_get_descriptor(dev, USB_DT_DEVICE, 0,
+				&dev->descriptor, sizeof(dev->descriptor));
+		config = dev->actconfig;
+		if (err < 0) snd_printdd("error usb_get_descriptor: %d\n", err);
+		err = usb_reset_configuration(dev);
+		if (err < 0) snd_printdd("error usb_reset_configuration: %d\n", err);
+		snd_printdd("extigy_boot: new boot length = %d\n",
+			    le16_to_cpu(get_cfg_desc(config)->wTotalLength));
+		return -ENODEV; /* quit this anyway */
+	}
+	return 0;
+}
+
+static int snd_usb_audigy2nx_boot_quirk(struct usb_device *dev)
+{
+	u8 buf = 1;
+
+	snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), 0x2a,
+			USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_OTHER,
+			0, 0, &buf, 1, 1000);
+	if (buf == 0) {
+		snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), 0x29,
+				USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_OTHER,
+				1, 2000, NULL, 0, 1000);
+		return -ENODEV;
+	}
+	return 0;
+}
+
+/*
+ * C-Media CM106/CM106+ have four 16-bit internal registers that are nicely
+ * documented in the device's data sheet.
+ */
+static int snd_usb_cm106_write_int_reg(struct usb_device *dev, int reg, u16 value)
+{
+	u8 buf[4];
+	buf[0] = 0x20;
+	buf[1] = value & 0xff;
+	buf[2] = (value >> 8) & 0xff;
+	buf[3] = reg;
+	return snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), USB_REQ_SET_CONFIGURATION,
+			       USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
+			       0, 0, &buf, 4, 1000);
+}
+
+static int snd_usb_cm106_boot_quirk(struct usb_device *dev)
+{
+	/*
+	 * Enable line-out driver mode, set headphone source to front
+	 * channels, enable stereo mic.
+	 */
+	return snd_usb_cm106_write_int_reg(dev, 2, 0x8004);
+}
+
+/*
+ * C-Media CM6206 is based on CM106 with two additional
+ * registers that are not documented in the data sheet.
+ * Values here are chosen based on sniffing USB traffic
+ * under Windows.
+ */
+static int snd_usb_cm6206_boot_quirk(struct usb_device *dev)
+{
+	int err, reg;
+	int val[] = {0x200c, 0x3000, 0xf800, 0x143f, 0x0000, 0x3000};
+
+	for (reg = 0; reg < ARRAY_SIZE(val); reg++) {
+		err = snd_usb_cm106_write_int_reg(dev, reg, val[reg]);
+		if (err < 0)
+			return err;
+	}
+
+	return err;
+}
+
+/*
+ * This call will put the synth in "USB send" mode, i.e it will send MIDI
+ * messages through USB (this is disabled at startup). The synth will
+ * acknowledge by sending a sysex on endpoint 0x85 and by displaying a USB
+ * sign on its LCD. Values here are chosen based on sniffing USB traffic
+ * under Windows.
+ */
+static int snd_usb_accessmusic_boot_quirk(struct usb_device *dev)
+{
+	int err, actual_length;
+
+	/* "midi send" enable */
+	static const u8 seq[] = { 0x4e, 0x73, 0x52, 0x01 };
+
+	void *buf = kmemdup(seq, ARRAY_SIZE(seq), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	err = usb_interrupt_msg(dev, usb_sndintpipe(dev, 0x05), buf,
+			ARRAY_SIZE(seq), &actual_length, 1000);
+	kfree(buf);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+/*
+ * Setup quirks
+ */
+#define AUDIOPHILE_SET			0x01 /* if set, parse device_setup */
+#define AUDIOPHILE_SET_DTS              0x02 /* if set, enable DTS Digital Output */
+#define AUDIOPHILE_SET_96K              0x04 /* 48-96KHz rate if set, 8-48KHz otherwise */
+#define AUDIOPHILE_SET_24B		0x08 /* 24bits sample if set, 16bits otherwise */
+#define AUDIOPHILE_SET_DI		0x10 /* if set, enable Digital Input */
+#define AUDIOPHILE_SET_MASK		0x1F /* bit mask for setup value */
+#define AUDIOPHILE_SET_24B_48K_DI	0x19 /* value for 24bits+48KHz+Digital Input */
+#define AUDIOPHILE_SET_24B_48K_NOTDI	0x09 /* value for 24bits+48KHz+No Digital Input */
+#define AUDIOPHILE_SET_16B_48K_DI	0x11 /* value for 16bits+48KHz+Digital Input */
+#define AUDIOPHILE_SET_16B_48K_NOTDI	0x01 /* value for 16bits+48KHz+No Digital Input */
+
+static int audiophile_skip_setting_quirk(struct snd_usb_audio *chip,
+					 int iface,
+					 int altno)
+{
+	/* Reset ALL ifaces to 0 altsetting.
+	 * Call it for every possible altsetting of every interface.
+	 */
+	usb_set_interface(chip->dev, iface, 0);
+
+	if (chip->setup & AUDIOPHILE_SET) {
+		if ((chip->setup & AUDIOPHILE_SET_DTS)
+		    && altno != 6)
+			return 1; /* skip this altsetting */
+		if ((chip->setup & AUDIOPHILE_SET_96K)
+		    && altno != 1)
+			return 1; /* skip this altsetting */
+		if ((chip->setup & AUDIOPHILE_SET_MASK) ==
+		    AUDIOPHILE_SET_24B_48K_DI && altno != 2)
+			return 1; /* skip this altsetting */
+		if ((chip->setup & AUDIOPHILE_SET_MASK) ==
+		    AUDIOPHILE_SET_24B_48K_NOTDI && altno != 3)
+			return 1; /* skip this altsetting */
+		if ((chip->setup & AUDIOPHILE_SET_MASK) ==
+		    AUDIOPHILE_SET_16B_48K_DI && altno != 4)
+			return 1; /* skip this altsetting */
+		if ((chip->setup & AUDIOPHILE_SET_MASK) ==
+		    AUDIOPHILE_SET_16B_48K_NOTDI && altno != 5)
+			return 1; /* skip this altsetting */
+	}
+
+	return 0; /* keep this altsetting */
+}
+
+int snd_usb_apply_interface_quirk(struct snd_usb_audio *chip,
+				  int iface,
+				  int altno)
+{
+	/* audiophile usb: skip altsets incompatible with device_setup */
+	if (chip->usb_id == USB_ID(0x0763, 0x2003))
+		return audiophile_skip_setting_quirk(chip, iface, altno);
+
+	return 0;
+}
+
+int snd_usb_apply_boot_quirk(struct usb_device *dev,
+			     struct usb_interface *intf,
+			     const struct snd_usb_audio_quirk *quirk)
+{
+	u32 id = USB_ID(le16_to_cpu(dev->descriptor.idVendor),
+			le16_to_cpu(dev->descriptor.idProduct));
+
+	/* SB Extigy needs special boot-up sequence */
+	/* if more models come, this will go to the quirk list. */
+	if (id == USB_ID(0x041e, 0x3000))
+		return snd_usb_extigy_boot_quirk(dev, intf);
+
+	/* SB Audigy 2 NX needs its own boot-up magic, too */
+	if (id == USB_ID(0x041e, 0x3020))
+		return snd_usb_audigy2nx_boot_quirk(dev);
+
+	/* C-Media CM106 / Turtle Beach Audio Advantage Roadie */
+	if (id == USB_ID(0x10f5, 0x0200))
+		return snd_usb_cm106_boot_quirk(dev);
+
+	/* C-Media CM6206 / CM106-Like Sound Device */
+	if (id == USB_ID(0x0d8c, 0x0102))
+		return snd_usb_cm6206_boot_quirk(dev);
+
+	/* Access Music VirusTI Desktop */
+	if (id == USB_ID(0x133e, 0x0815))
+		return snd_usb_accessmusic_boot_quirk(dev);
+
+	return 0;
+}
+
+/*
+ * check if the device uses big-endian samples
+ */
+int snd_usb_is_big_endian_format(struct snd_usb_audio *chip, struct audioformat *fp)
+{
+	switch (chip->usb_id) {
+	case USB_ID(0x0763, 0x2001): /* M-Audio Quattro: captured data only */
+		if (fp->endpoint & USB_DIR_IN)
+			return 1;
+		break;
+	case USB_ID(0x0763, 0x2003): /* M-Audio Audiophile USB */
+		if (chip->setup == 0x00 ||
+		    fp->altsetting==1 || fp->altsetting==2 || fp->altsetting==3)
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * For E-Mu 0404USB/0202USB/TrackerPre sample rate should be set for device,
+ * not for interface.
+ */
+
+enum {
+	EMU_QUIRK_SR_44100HZ = 0,
+	EMU_QUIRK_SR_48000HZ,
+	EMU_QUIRK_SR_88200HZ,
+	EMU_QUIRK_SR_96000HZ,
+	EMU_QUIRK_SR_176400HZ,
+	EMU_QUIRK_SR_192000HZ
+};
+
+static void set_format_emu_quirk(struct snd_usb_substream *subs,
+				 struct audioformat *fmt)
+{
+	unsigned char emu_samplerate_id = 0;
+
+	/* When capture is active
+	 * sample rate shouldn't be changed
+	 * by playback substream
+	 */
+	if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK) {
+		if (subs->stream->substream[SNDRV_PCM_STREAM_CAPTURE].interface != -1)
+			return;
+	}
+
+	switch (fmt->rate_min) {
+	case 48000:
+		emu_samplerate_id = EMU_QUIRK_SR_48000HZ;
+		break;
+	case 88200:
+		emu_samplerate_id = EMU_QUIRK_SR_88200HZ;
+		break;
+	case 96000:
+		emu_samplerate_id = EMU_QUIRK_SR_96000HZ;
+		break;
+	case 176400:
+		emu_samplerate_id = EMU_QUIRK_SR_176400HZ;
+		break;
+	case 192000:
+		emu_samplerate_id = EMU_QUIRK_SR_192000HZ;
+		break;
+	default:
+		emu_samplerate_id = EMU_QUIRK_SR_44100HZ;
+		break;
+	}
+	snd_emuusb_set_samplerate(subs->stream->chip, emu_samplerate_id);
+}
+
+void snd_usb_set_format_quirk(struct snd_usb_substream *subs,
+			      struct audioformat *fmt)
+{
+	switch (subs->stream->chip->usb_id) {
+	case USB_ID(0x041e, 0x3f02): /* E-Mu 0202 USB */
+	case USB_ID(0x041e, 0x3f04): /* E-Mu 0404 USB */
+	case USB_ID(0x041e, 0x3f0a): /* E-Mu Tracker Pre */
+		set_format_emu_quirk(subs, fmt);
+		break;
+	}
+}
+