This device has a broken vendor-specific altsetting for interface 1,
where endpoint 0x85 is declared as an isochronous endpoint despite being
used by interface 2 for audio capture.

Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  idVendor           0x0926
  idProduct          0x0202
  bcdDevice            1.00
  iManufacturer           1 Sound Devices
  iProduct                2 USBPre2
  iSerial                 3 [...]
  bNumConfigurations      1

[...]

    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       3
      bNumEndpoints           2
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0
      bInterfaceProtocol      0
      iInterface              0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x85  EP 5 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0126  1x 294 bytes
        bInterval               1

[...]

    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       1
      bNumEndpoints           1
      bInterfaceClass         1 Audio
      bInterfaceSubClass      2 Streaming
      bInterfaceProtocol      0
      iInterface              0
      AudioStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (AS_GENERAL)
        bTerminalLink           4
        bDelay                  1 frames
        wFormatTag         0x0001 PCM
      AudioStreaming Interface Descriptor:
        bLength                26
        bDescriptorType        36
        bDescriptorSubtype      2 (FORMAT_TYPE)
        bFormatType             1 (FORMAT_TYPE_I)
        bNrChannels             2
        bSubframeSize           2
        bBitResolution         16
        bSamFreqType            6 Discrete
        tSamFreq[ 0]         8000
        tSamFreq[ 1]        16000
        tSamFreq[ 2]        24000
        tSamFreq[ 3]        32000
        tSamFreq[ 4]        44100
        tSamFreq[ 5]        48000
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x85  EP 5 IN
        bmAttributes            5
          Transfer Type            Isochronous
          Synch Type               Asynchronous
          Usage Type               Data
        wMaxPacketSize     0x0126  1x 294 bytes
        bInterval               4
        bRefresh                0
        bSynchAddress           0
        AudioStreaming Endpoint Descriptor:
          bLength                 7
          bDescriptorType        37
          bDescriptorSubtype      1 (EP_GENERAL)
          bmAttributes         0x01
            Sampling Frequency
          bLockDelayUnits         2 Decoded PCM samples
          wLockDelay         0x0000

Since commit 3e4f8e21 ("USB: core: fix check for duplicate
endpoints") USB core ignores any duplicate endpoints found during
descriptor parsing, but in this case we need to ignore the first
instance in order to avoid breaking the audio capture interface.

Fixes: 3e4f8e21 ("USB: core: fix check for duplicate endpoints")
Cc: stable <stable@vger.kernel.org>
Reported-by: edes <edes@gmx.net>
Tested-by: edes <edes@gmx.net>
Link: https://lore.kernel.org/r/20200201105829.5682c887@acme7.acmenetSigned-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200203153830.26394-3-johan@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>