On Fri, 21 Apr 2023 17:16:59 +0200, Chris Down wrote: > > Takashi Iwai writes: > > Hrm, is "usb 3-7.1.4" really the USB audio device? The previous > > errors like "Unable to submit urb #2..." are certainly for USB audio, > > and those are with "usb 3-7.4". > > There are two USB audio devices -- 3-7.1.4 is input, 3-7.4 is output. > > % dmesg --notime | grep -e 'usb 3-7.4' -e 'usb 3-7.1.4' | grep Product: | sort | uniq > usb 3-7.1.4: Product: USB2.0 Microphone > usb 3-7.4: Product: USB Audio Device Ah I see. Then those are two different sound cards? The repeated call of usb_set_interface() might be avoided by the additional check like below. But it's still puzzling how it happens, because the only caller of endpoint_set_interface() you modified is snd_usb_endpoint_prepare(), and it's called only from snd_usb_pcm_prepare(). And, snd_usb_pcm_preapre() has the snd_usb_lock_shutdown() call, which does the check of the card->shutdown flag that should be set by the USB disconnection callback... thanks, Takashi -- 8< -- --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -911,6 +911,9 @@ static int endpoint_set_interface(struct snd_usb_audio *chip, if (ep->iface_ref->altset == altset) return 0; + /* already disconnected? */ + if (unlikely(atomic_read(&chip->shutdown))) + return -ENODEV; usb_audio_dbg(chip, "Setting usb interface %d:%d for EP 0x%x\n", ep->iface, altset, ep->ep_num);
