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linux/sound/usb/quirks.h
Takashi Iwai 6392dcd1d0 ALSA: usb-audio: Register card at the last interface
The USB-audio driver matches per interface, and as default, it
registers the card instance at the very first instance.  This can be a
problem for the devices that have multiple interfaces to be probed, as
the udev rule isn't applied properly for the later appearing
interfaces.  Although we introduced the delayed_register option and
the quirks for covering those shortcomings, it's nothing but a
workaround for specific devices.

This patch is an another attempt to fix the problem in a more generic
way.  Now the driver checks the whole USB device descriptor at the
very first time when an interface is attached to a sound card.  It
looks at each matching interface in the descriptor and remembers the
last matching one.  The snd_card_register() is invoked only when this
last interface is probed.

After this change, the quirks for the delayed registration become
superfluous, hence they are removed along with the patch.  OTOH, the
delayed_register option is still kept, as it might be useful for some
corner cases (e.g. a special driver overtakes the interface probe from
the standard driver, and the last interface probe may miss).

Link: https://lore.kernel.org/r/20220904161247.16461-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2022-09-06 11:04:56 +02:00

54 lines
1.6 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __USBAUDIO_QUIRKS_H
#define __USBAUDIO_QUIRKS_H
struct audioformat;
struct snd_usb_endpoint;
struct snd_usb_substream;
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);
int snd_usb_apply_interface_quirk(struct snd_usb_audio *chip,
int iface,
int altno);
int snd_usb_apply_boot_quirk(struct usb_device *dev,
struct usb_interface *intf,
const struct snd_usb_audio_quirk *quirk,
unsigned int usb_id);
int snd_usb_apply_boot_quirk_once(struct usb_device *dev,
struct usb_interface *intf,
const struct snd_usb_audio_quirk *quirk,
unsigned int usb_id);
void snd_usb_set_format_quirk(struct snd_usb_substream *subs,
const struct audioformat *fmt);
int snd_usb_is_big_endian_format(struct snd_usb_audio *chip,
const struct audioformat *fp);
void snd_usb_endpoint_start_quirk(struct snd_usb_endpoint *ep);
void snd_usb_ctl_msg_quirk(struct usb_device *dev, unsigned int pipe,
__u8 request, __u8 requesttype, __u16 value,
__u16 index, void *data, __u16 size);
int snd_usb_select_mode_quirk(struct snd_usb_audio *chip,
const struct audioformat *fmt);
u64 snd_usb_interface_dsd_format_quirks(struct snd_usb_audio *chip,
struct audioformat *fp,
unsigned int sample_bytes);
void snd_usb_audioformat_attributes_quirk(struct snd_usb_audio *chip,
struct audioformat *fp,
int stream);
void snd_usb_init_quirk_flags(struct snd_usb_audio *chip);
#endif /* __USBAUDIO_QUIRKS_H */