From 6392dcd1d0c7034ccf630ec55fc9e5810ecadf3b Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Sun, 4 Sep 2022 18:12:47 +0200 Subject: 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 --- sound/usb/card.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) (limited to 'sound/usb/card.c') 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; -- cgit v1.2.3