[PATCH 0/2] ALSA: usb-audio: Add quirks for HP Elite x3 Lap Dock

[Rong Zhang]

The HP Elite x3 Lap Dock is a laptop-like external display device with a
FHD screen, a keyboard, and a MT touchpad. It can be connected via USB-C
or Miracast. As an e-waste collector, I recently brought one for 69 CNY
(10.2 USD). The price already indicates how broken the device's design
and compatibility are ;-P

When connecting via USB-C, the video source is, of course, DisplayPort
Alternate Mode. However, the audio source has nothing to do with the
DisplayPort signal and is actually from a builtin UAC device.

The builtin UAC device provides three Alternate Settings:

- 1:1 - Capture, S16_LE, 8000/32000/44100/48000Hz
- 2:1 - Playback, S16_LE, 48000Hz
- 2:2 - Playback, S24_3LE, 48000Hz

Unfortunately, the last one is broken because:

- it doesn't accept SET_CUR(SAMPLE_RATE). QUIRK_FLAG_FIXED_RATE works
  around it, however...
- it constantly produces severe harmonic distortion once the capture
  stream is also opened. The interface 2 must be closed and reopened to
  make it recover. IOW, simply closing the capture stream makes no
  difference.

Considering that S24_3LE offers no additional benefit on small speakers
compared to S16_LE, and 2:1 is always usable as an alternative, skip 2:2
to get rid of the trouble.

Setting chip->setup to any non-default value disables the fixup and
reenables 2:2 (in this case QUIRK_FLAG_FIXED_RATE is required).

Quirky device sample:

  usb 7-1.4: new full-speed USB device number 50 using xhci_hcd
  usb 7-1.4: New USB device found, idVendor=03f0, idProduct=0c56, bcdDevice= 0.00
  usb 7-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=0
  usb 7-1.4: Product: HP Elite x3 Lap Dock
  usb 7-1.4: Manufacturer: HP
  usb 7-1.4: Found last interface = 0
  usb 7-1.4: 1:1: add audio endpoint 0x81
  usb 7-1.4: Creating new data endpoint #81
  usb 7-1.4: 1:1 Set sample rate 48000, clock 0
  usb 7-1.4: 2:1: add audio endpoint 0x1
  usb 7-1.4: Creating new data endpoint #1
  usb 7-1.4: 2:1 Set sample rate 48000, clock 0
  usb 7-1.4: 2:2: add audio endpoint 0x1
  usb 7-1.4: 2:2 Set sample rate 48000, clock 0
  usb 7-1.4: 2:2: cannot set freq 48000 to ep 0x1
  usb 7-1.4: [9] FU [Sidetone Playback Switch] ch = 1, val = 0/1/1
  usb 7-1.4: cannot set ctl value: req = 0x4, wValue = 0x200, wIndex = 0x900, type = 4, data = 0x40/0x0
  usb 7-1.4: [9] FU [Sidetone Playback Volume] ch = 1, val = -17664/0/128
  usb 7-1.4: [2] FU [Headset Playback Switch] ch = 1, val = 0/1/1
  usb 7-1.4: [2] FU [Headset Playback Volume] ch = 2, val = -18944/0/1
  usb 7-1.4: [6] FU [Headset Capture Switch] ch = 1, val = 0/1/1
  usb 7-1.4: [6] FU [Headset Capture Volume] ch = 2, val = -18944/0/1
  input: HP HP Elite x3 Lap Dock Consumer Control as /devices/pci0000:00/0000:00:08.3/0000:c9:00.4/usb7/7-1/7-1.4/7-1.4:1.3/0003:03F0:0C56.0033/input/input129
  input: HP HP Elite x3 Lap Dock as /devices/pci0000:00/0000:00:08.3/0000:c9:00.4/usb7/7-1/7-1.4/7-1.4:1.3/0003:03F0:0C56.0033/input/input130
  hid-generic 0003:03F0:0C56.0033: input,hiddev100,hidraw8: USB HID v1.11 Device [HP HP Elite x3 Lap Dock] on usb-0000:c9:00.4-1.4/input3

Signed-off-by: Rong Zhang <i@xxxxxxxx>
---
Rong Zhang (2):
      ALSA: usb-audio: Convert snd_usb_apply_interface_quirk() into a switch statement
      ALSA: usb-audio: Add quirks for HP Elite x3 Lap Dock

 sound/usb/quirks.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 46 insertions(+), 6 deletions(-)
---
base-commit: df2908090cda368b01ff43709f51890076c56157
change-id: 47d1988d-uac-hp-elite-x3-lap-dock-59fc42bf91c2

Thanks,
Rong