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author | Takashi Iwai <tiwai@suse.de> | 2022-09-04 18:12:47 +0200 |
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committer | Takashi Iwai <tiwai@suse.de> | 2022-09-06 11:04:56 +0200 |
commit | 6392dcd1d0c7034ccf630ec55fc9e5810ecadf3b (patch) | |
tree | 1a2fcdd000bce3797068d53e21adf786d3934bef /sound/usb/card.c | |
parent | 16c5cde20e304cd900371b140cd53ecafe8d3de5 (diff) | |
download | linux-stable-6392dcd1d0c7034ccf630ec55fc9e5810ecadf3b.tar.gz linux-stable-6392dcd1d0c7034ccf630ec55fc9e5810ecadf3b.tar.bz2 linux-stable-6392dcd1d0c7034ccf630ec55fc9e5810ecadf3b.zip |
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>
Diffstat (limited to 'sound/usb/card.c')
-rw-r--r-- | sound/usb/card.c | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/sound/usb/card.c b/sound/usb/card.c index 706d249a9ad6..3aea241435fb 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -690,7 +690,7 @@ static bool get_alias_id(struct usb_device *dev, unsigned int *id) return false; } -static bool check_delayed_register_option(struct snd_usb_audio *chip, int iface) +static int check_delayed_register_option(struct snd_usb_audio *chip) { int i; unsigned int id, inum; @@ -699,14 +699,31 @@ static bool check_delayed_register_option(struct snd_usb_audio *chip, int iface) if (delayed_register[i] && sscanf(delayed_register[i], "%x:%x", &id, &inum) == 2 && id == chip->usb_id) - return iface < inum; + return inum; } - return false; + return -1; } static const struct usb_device_id usb_audio_ids[]; /* defined below */ +/* look for the last interface that matches with our ids and remember it */ +static void find_last_interface(struct snd_usb_audio *chip) +{ + struct usb_host_config *config = chip->dev->actconfig; + struct usb_interface *intf; + int i; + + if (!config) + return; + for (i = 0; i < config->desc.bNumInterfaces; i++) { + intf = config->interface[i]; + if (usb_match_id(intf, usb_audio_ids)) + chip->last_iface = intf->altsetting[0].desc.bInterfaceNumber; + } + usb_audio_dbg(chip, "Found last interface = %d\n", chip->last_iface); +} + /* look for the corresponding quirk */ static const struct snd_usb_audio_quirk * get_alias_quirk(struct usb_device *dev, unsigned int id) @@ -813,6 +830,7 @@ static int usb_audio_probe(struct usb_interface *intf, err = -ENODEV; goto __error; } + find_last_interface(chip); } if (chip->num_interfaces >= MAX_CARD_INTERFACES) { @@ -862,11 +880,11 @@ static int usb_audio_probe(struct usb_interface *intf, chip->need_delayed_register = false; /* clear again */ } - /* we are allowed to call snd_card_register() many times, but first - * check to see if a device needs to skip it or do anything special + /* register card if we reach to the last interface or to the specified + * one given via option */ - if (!snd_usb_registration_quirk(chip, ifnum) && - !check_delayed_register_option(chip, ifnum)) { + if (check_delayed_register_option(chip) == ifnum || + chip->last_iface == ifnum) { err = snd_card_register(chip->card); if (err < 0) goto __error; |