docs: usb: rename files to .rst and add them to drivers-api

While there are a mix of things here, most of the stuff
were written from Kernel developer's PoV. So, add them to
the driver-api book.

A follow up for this patch would be to move documents from
there that are specific to sysadmins, adding them to the
admin-guide.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Johan Hovold <johan@kernel.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 0 insertions, 934 deletions

diff --git a/Documentation/usb/gadget-testing.txt b/Documentation/usb/gadget-testing.txt
deleted file mode 100644
index 7d7f2340af42..000000000000
--- a/Documentation/usb/gadget-testing.txt
+++ /dev/null
@@ -1,934 +0,0 @@
-==============
-Gadget Testing
-==============
-
-This file summarizes information on basic testing of USB functions
-provided by gadgets.
-
-.. contents
-
-   1. ACM function
-   2. ECM function
-   3. ECM subset function
-   4. EEM function
-   5. FFS function
-   6. HID function
-   7. LOOPBACK function
-   8. MASS STORAGE function
-   9. MIDI function
-   10. NCM function
-   11. OBEX function
-   12. PHONET function
-   13. RNDIS function
-   14. SERIAL function
-   15. SOURCESINK function
-   16. UAC1 function (legacy implementation)
-   17. UAC2 function
-   18. UVC function
-   19. PRINTER function
-   20. UAC1 function (new API)
-
-
-1. ACM function
-===============
-
-The function is provided by usb_f_acm.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "acm".
-The ACM function provides just one attribute in its function directory:
-
-	port_num
-
-The attribute is read-only.
-
-There can be at most 4 ACM/generic serial/OBEX ports in the system.
-
-
-Testing the ACM function
-------------------------
-
-On the host::
-
-	cat > /dev/ttyACM<X>
-
-On the device::
-
-	cat /dev/ttyGS<Y>
-
-then the other way round
-
-On the device::
-
-	cat > /dev/ttyGS<Y>
-
-On the host::
-
-	cat /dev/ttyACM<X>
-
-2. ECM function
-===============
-
-The function is provided by usb_f_ecm.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "ecm".
-The ECM function provides these attributes in its function directory:
-
-	=============== ==================================================
-	ifname		network device interface name associated with this
-			function instance
-	qmult		queue length multiplier for high and super speed
-	host_addr	MAC address of host's end of this
-			Ethernet over USB link
-	dev_addr	MAC address of device's end of this
-			Ethernet over USB link
-	=============== ==================================================
-
-and after creating the functions/ecm.<instance name> they contain default
-values: qmult is 5, dev_addr and host_addr are randomly selected.
-Except for ifname they can be written to until the function is linked to a
-configuration. The ifname is read-only and contains the name of the interface
-which was assigned by the net core, e. g. usb0.
-
-Testing the ECM function
-------------------------
-
-Configure IP addresses of the device and the host. Then:
-
-On the device::
-
-	ping <host's IP>
-
-On the host::
-
-	ping <device's IP>
-
-3. ECM subset function
-======================
-
-The function is provided by usb_f_ecm_subset.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "geth".
-The ECM subset function provides these attributes in its function directory:
-
-	=============== ==================================================
-	ifname		network device interface name associated with this
-			function instance
-	qmult		queue length multiplier for high and super speed
-	host_addr	MAC address of host's end of this
-			Ethernet over USB link
-	dev_addr	MAC address of device's end of this
-			Ethernet over USB link
-	=============== ==================================================
-
-and after creating the functions/ecm.<instance name> they contain default
-values: qmult is 5, dev_addr and host_addr are randomly selected.
-Except for ifname they can be written to until the function is linked to a
-configuration. The ifname is read-only and contains the name of the interface
-which was assigned by the net core, e. g. usb0.
-
-Testing the ECM subset function
--------------------------------
-
-Configure IP addresses of the device and the host. Then:
-
-On the device::
-
-	ping <host's IP>
-
-On the host::
-
-	ping <device's IP>
-
-4. EEM function
-===============
-
-The function is provided by usb_f_eem.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "eem".
-The EEM function provides these attributes in its function directory:
-
-	=============== ==================================================
-	ifname		network device interface name associated with this
-			function instance
-	qmult		queue length multiplier for high and super speed
-	host_addr	MAC address of host's end of this
-			Ethernet over USB link
-	dev_addr	MAC address of device's end of this
-			Ethernet over USB link
-	=============== ==================================================
-
-and after creating the functions/eem.<instance name> they contain default
-values: qmult is 5, dev_addr and host_addr are randomly selected.
-Except for ifname they can be written to until the function is linked to a
-configuration. The ifname is read-only and contains the name of the interface
-which was assigned by the net core, e. g. usb0.
-
-Testing the EEM function
-------------------------
-
-Configure IP addresses of the device and the host. Then:
-
-On the device::
-
-	ping <host's IP>
-
-On the host::
-
-	ping <device's IP>
-
-5. FFS function
-===============
-
-The function is provided by usb_f_fs.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "ffs".
-The function directory is intentionally empty and not modifiable.
-
-After creating the directory there is a new instance (a "device") of FunctionFS
-available in the system. Once a "device" is available, the user should follow
-the standard procedure for using FunctionFS (mount it, run the userspace
-process which implements the function proper). The gadget should be enabled
-by writing a suitable string to usb_gadget/<gadget>/UDC.
-
-Testing the FFS function
-------------------------
-
-On the device: start the function's userspace daemon, enable the gadget
-
-On the host: use the USB function provided by the device
-
-6. HID function
-===============
-
-The function is provided by usb_f_hid.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "hid".
-The HID function provides these attributes in its function directory:
-
-	=============== ===========================================
-	protocol	HID protocol to use
-	report_desc	data to be used in HID reports, except data
-			passed with /dev/hidg<X>
-	report_length	HID report length
-	subclass	HID subclass to use
-	=============== ===========================================
-
-For a keyboard the protocol and the subclass are 1, the report_length is 8,
-while the report_desc is::
-
-  $ hd my_report_desc
-  00000000  05 01 09 06 a1 01 05 07  19 e0 29 e7 15 00 25 01  |..........)...%.|
-  00000010  75 01 95 08 81 02 95 01  75 08 81 03 95 05 75 01  |u.......u.....u.|
-  00000020  05 08 19 01 29 05 91 02  95 01 75 03 91 03 95 06  |....).....u.....|
-  00000030  75 08 15 00 25 65 05 07  19 00 29 65 81 00 c0     |u...%e....)e...|
-  0000003f
-
-Such a sequence of bytes can be stored to the attribute with echo::
-
-  $ echo -ne \\x05\\x01\\x09\\x06\\xa1.....
-
-Testing the HID function
-------------------------
-
-Device:
-
-- create the gadget
-- connect the gadget to a host, preferably not the one used
-  to control the gadget
-- run a program which writes to /dev/hidg<N>, e.g.
-  a userspace program found in Documentation/usb/gadget_hid.txt::
-
-	$ ./hid_gadget_test /dev/hidg0 keyboard
-
-Host:
-
-- observe the keystrokes from the gadget
-
-7. LOOPBACK function
-====================
-
-The function is provided by usb_f_ss_lb.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "Loopback".
-The LOOPBACK function provides these attributes in its function directory:
-
-	=============== =======================
-	qlen		depth of loopback queue
-	bulk_buflen	buffer length
-	=============== =======================
-
-Testing the LOOPBACK function
------------------------------
-
-device: run the gadget
-
-host: test-usb (tools/usb/testusb.c)
-
-8. MASS STORAGE function
-========================
-
-The function is provided by usb_f_mass_storage.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "mass_storage".
-The MASS STORAGE function provides these attributes in its directory:
-files:
-
-	=============== ==============================================
-	stall		Set to permit function to halt bulk endpoints.
-			Disabled on some USB devices known not to work
-			correctly. You should set it to true.
-	num_buffers	Number of pipeline buffers. Valid numbers
-			are 2..4. Available only if
-			CONFIG_USB_GADGET_DEBUG_FILES is set.
-	=============== ==============================================
-
-and a default lun.0 directory corresponding to SCSI LUN #0.
-
-A new lun can be added with mkdir::
-
-	$ mkdir functions/mass_storage.0/partition.5
-
-Lun numbering does not have to be continuous, except for lun #0 which is
-created by default. A maximum of 8 luns can be specified and they all must be
-named following the <name>.<number> scheme. The numbers can be 0..8.
-Probably a good convention is to name the luns "lun.<number>",
-although it is not mandatory.
-
-In each lun directory there are the following attribute files:
-
-	=============== ==============================================
-	file		The path to the backing file for the LUN.
-			Required if LUN is not marked as removable.
-	ro		Flag specifying access to the LUN shall be
-			read-only. This is implied if CD-ROM emulation
-			is enabled as well as when it was impossible
-			to open "filename" in R/W mode.
-	removable	Flag specifying that LUN shall be indicated as
-			being removable.
-	cdrom		Flag specifying that LUN shall be reported as
-			being a CD-ROM.
-	nofua		Flag specifying that FUA flag
-			in SCSI WRITE(10,12)
-	=============== ==============================================
-
-Testing the MASS STORAGE function
----------------------------------
-
-device: connect the gadget, enable it
-host: dmesg, see the USB drives appear (if system configured to automatically
-mount)
-
-9. MIDI function
-================
-
-The function is provided by usb_f_midi.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "midi".
-The MIDI function provides these attributes in its function directory:
-
-	=============== ====================================
-	buflen		MIDI buffer length
-	id		ID string for the USB MIDI adapter
-	in_ports	number of MIDI input ports
-	index		index value for the USB MIDI adapter
-	out_ports	number of MIDI output ports
-	qlen		USB read request queue length
-	=============== ====================================
-
-Testing the MIDI function
--------------------------
-
-There are two cases: playing a mid from the gadget to
-the host and playing a mid from the host to the gadget.
-
-1) Playing a mid from the gadget to the host:
-
-host::
-
-  $ arecordmidi -l
-   Port    Client name                      Port name
-   14:0    Midi Through                     Midi Through Port-0
-   24:0    MIDI Gadget                      MIDI Gadget MIDI 1
-  $ arecordmidi -p 24:0 from_gadget.mid
-
-gadget::
-
-  $ aplaymidi -l
-   Port    Client name                      Port name
-   20:0    f_midi                           f_midi
-
-  $ aplaymidi -p 20:0 to_host.mid
-
-2) Playing a mid from the host to the gadget
-
-gadget::
-
-  $ arecordmidi -l
-   Port    Client name                      Port name
-   20:0    f_midi                           f_midi
-
-  $ arecordmidi -p 20:0 from_host.mid
-
-host::
-
-  $ aplaymidi -l
-   Port    Client name                      Port name
-   14:0    Midi Through                     Midi Through Port-0
-   24:0    MIDI Gadget                      MIDI Gadget MIDI 1
-
-  $ aplaymidi -p24:0 to_gadget.mid
-
-The from_gadget.mid should sound identical to the to_host.mid.
-
-The from_host.id should sound identical to the to_gadget.mid.
-
-MIDI files can be played to speakers/headphones with e.g. timidity installed::
-
-  $ aplaymidi -l
-   Port    Client name                      Port name
-   14:0    Midi Through                     Midi Through Port-0
-   24:0    MIDI Gadget                      MIDI Gadget MIDI 1
-  128:0    TiMidity                         TiMidity port 0
-  128:1    TiMidity                         TiMidity port 1
-  128:2    TiMidity                         TiMidity port 2
-  128:3    TiMidity                         TiMidity port 3
-
-  $ aplaymidi -p 128:0 file.mid
-
-MIDI ports can be logically connected using the aconnect utility, e.g.::
-
-  $ aconnect 24:0 128:0 # try it on the host
-
-After the gadget's MIDI port is connected to timidity's MIDI port,
-whatever is played at the gadget side with aplaymidi -l is audible
-in host's speakers/headphones.
-
-10. NCM function
-================
-
-The function is provided by usb_f_ncm.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "ncm".
-The NCM function provides these attributes in its function directory:
-
-	=============== ==================================================
-	ifname		network device interface name associated with this
-			function instance
-	qmult		queue length multiplier for high and super speed
-	host_addr	MAC address of host's end of this
-			Ethernet over USB link
-	dev_addr	MAC address of device's end of this
-			Ethernet over USB link
-	=============== ==================================================
-
-and after creating the functions/ncm.<instance name> they contain default
-values: qmult is 5, dev_addr and host_addr are randomly selected.
-Except for ifname they can be written to until the function is linked to a
-configuration. The ifname is read-only and contains the name of the interface
-which was assigned by the net core, e. g. usb0.
-
-Testing the NCM function
-------------------------
-
-Configure IP addresses of the device and the host. Then:
-
-On the device::
-
-	ping <host's IP>
-
-On the host::
-
-	ping <device's IP>
-
-11. OBEX function
-=================
-
-The function is provided by usb_f_obex.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "obex".
-The OBEX function provides just one attribute in its function directory:
-
-	port_num
-
-The attribute is read-only.
-
-There can be at most 4 ACM/generic serial/OBEX ports in the system.
-
-Testing the OBEX function
--------------------------
-
-On device::
-
-	seriald -f /dev/ttyGS<Y> -s 1024
-
-On host::
-
-	serialc -v <vendorID> -p <productID> -i<interface#> -a1 -s1024 \
-                -t<out endpoint addr> -r<in endpoint addr>
-
-where seriald and serialc are Felipe's utilities found here:
-
-	https://github.com/felipebalbi/usb-tools.git master
-
-12. PHONET function
-===================
-
-The function is provided by usb_f_phonet.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "phonet".
-The PHONET function provides just one attribute in its function directory:
-
-	=============== ==================================================
-	ifname		network device interface name associated with this
-			function instance
-	=============== ==================================================
-
-Testing the PHONET function
----------------------------
-
-It is not possible to test the SOCK_STREAM protocol without a specific piece
-of hardware, so only SOCK_DGRAM has been tested. For the latter to work,
-in the past I had to apply the patch mentioned here:
-
-http://www.spinics.net/lists/linux-usb/msg85689.html
-
-These tools are required:
-
-git://git.gitorious.org/meego-cellular/phonet-utils.git
-
-On the host::
-
-	$ ./phonet -a 0x10 -i usbpn0
-	$ ./pnroute add 0x6c usbpn0
-	$./pnroute add 0x10 usbpn0
-	$ ifconfig usbpn0 up
-
-On the device::
-
-	$ ./phonet -a 0x6c -i upnlink0
-	$ ./pnroute add 0x10 upnlink0
-	$ ifconfig upnlink0 up
-
-Then a test program can be used::
-
-	http://www.spinics.net/lists/linux-usb/msg85690.html
-
-On the device::
-
-	$ ./pnxmit -a 0x6c -r
-
-On the host::
-
-	$ ./pnxmit -a 0x10 -s 0x6c
-
-As a result some data should be sent from host to device.
-Then the other way round:
-
-On the host::
-
-	$ ./pnxmit -a 0x10 -r
-
-On the device::
-
-	$ ./pnxmit -a 0x6c -s 0x10
-
-13. RNDIS function
-==================
-
-The function is provided by usb_f_rndis.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "rndis".
-The RNDIS function provides these attributes in its function directory:
-
-	=============== ==================================================
-	ifname		network device interface name associated with this
-			function instance
-	qmult		queue length multiplier for high and super speed
-	host_addr	MAC address of host's end of this
-			Ethernet over USB link
-	dev_addr	MAC address of device's end of this
-			Ethernet over USB link
-	=============== ==================================================
-
-and after creating the functions/rndis.<instance name> they contain default
-values: qmult is 5, dev_addr and host_addr are randomly selected.
-Except for ifname they can be written to until the function is linked to a
-configuration. The ifname is read-only and contains the name of the interface
-which was assigned by the net core, e. g. usb0.
-
-Testing the RNDIS function
---------------------------
-
-Configure IP addresses of the device and the host. Then:
-
-On the device::
-
-	ping <host's IP>
-
-On the host::
-
-	ping <device's IP>
-
-14. SERIAL function
-===================
-
-The function is provided by usb_f_gser.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "gser".
-The SERIAL function provides just one attribute in its function directory:
-
-	port_num
-
-The attribute is read-only.
-
-There can be at most 4 ACM/generic serial/OBEX ports in the system.
-
-Testing the SERIAL function
----------------------------
-
-On host::
-
-	insmod usbserial
-	echo VID PID >/sys/bus/usb-serial/drivers/generic/new_id
-
-On host::
-
-	cat > /dev/ttyUSB<X>
-
-On target::
-
-	cat /dev/ttyGS<Y>
-
-then the other way round
-
-On target::
-
-	cat > /dev/ttyGS<Y>
-
-On host::
-
-	cat /dev/ttyUSB<X>
-
-15. SOURCESINK function
-=======================
-
-The function is provided by usb_f_ss_lb.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "SourceSink".
-The SOURCESINK function provides these attributes in its function directory:
-
-	=============== ==================================
-	pattern		0 (all zeros), 1 (mod63), 2 (none)
-	isoc_interval	1..16
-	isoc_maxpacket	0 - 1023 (fs), 0 - 1024 (hs/ss)
-	isoc_mult	0..2 (hs/ss only)
-	isoc_maxburst	0..15 (ss only)
-	bulk_buflen	buffer length
-	bulk_qlen	depth of queue for bulk
-	iso_qlen	depth of queue for iso
-	=============== ==================================
-
-Testing the SOURCESINK function
--------------------------------
-
-device: run the gadget
-
-host: test-usb (tools/usb/testusb.c)
-
-
-16. UAC1 function (legacy implementation)
-=========================================
-
-The function is provided by usb_f_uac1_legacy.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory
-is "uac1_legacy".
-The uac1 function provides these attributes in its function directory:
-
-	=============== ====================================
-	audio_buf_size	audio buffer size
-	fn_cap		capture pcm device file name
-	fn_cntl		control device file name
-	fn_play		playback pcm device file name
-	req_buf_size	ISO OUT endpoint request buffer size
-	req_count	ISO OUT endpoint request count
-	=============== ====================================
-
-The attributes have sane default values.
-
-Testing the UAC1 function
--------------------------
-
-device: run the gadget
-
-host::
-
-	aplay -l # should list our USB Audio Gadget
-
-17. UAC2 function
-=================
-
-The function is provided by usb_f_uac2.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "uac2".
-The uac2 function provides these attributes in its function directory:
-
-	=============== ====================================================
-	c_chmask	capture channel mask
-	c_srate		capture sampling rate
-	c_ssize		capture sample size (bytes)
-	p_chmask	playback channel mask
-	p_srate		playback sampling rate
-	p_ssize		playback sample size (bytes)
-	req_number	the number of pre-allocated request for both capture
-			and playback
-	=============== ====================================================
-
-The attributes have sane default values.
-
-Testing the UAC2 function
--------------------------
-
-device: run the gadget
-host: aplay -l # should list our USB Audio Gadget
-
-This function does not require real hardware support, it just
-sends a stream of audio data to/from the host. In order to
-actually hear something at the device side, a command similar
-to this must be used at the device side::
-
-	$ arecord -f dat -t wav -D hw:2,0 | aplay -D hw:0,0 &
-
-e.g.::
-
-	$ arecord -f dat -t wav -D hw:CARD=UAC2Gadget,DEV=0 | \
-	  aplay -D default:CARD=OdroidU3
-
-18. UVC function
-================
-
-The function is provided by usb_f_uvc.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "uvc".
-The uvc function provides these attributes in its function directory:
-
-	=================== ================================================
-	streaming_interval  interval for polling endpoint for data transfers
-	streaming_maxburst  bMaxBurst for super speed companion descriptor
-	streaming_maxpacket maximum packet size this endpoint is capable of
-			    sending or receiving when this configuration is
-			    selected
-	=================== ================================================
-
-There are also "control" and "streaming" subdirectories, each of which contain
-a number of their subdirectories. There are some sane defaults provided, but
-the user must provide the following:
-
-	================== ====================================================
-	control header     create in control/header, link from control/class/fs
-			   and/or control/class/ss
-	streaming header   create in streaming/header, link from
-			   streaming/class/fs and/or streaming/class/hs and/or
-			   streaming/class/ss
-	format description create in streaming/mjpeg and/or
-			   streaming/uncompressed
-	frame description  create in streaming/mjpeg/<format> and/or in
-			   streaming/uncompressed/<format>
-	================== ====================================================
-
-Each frame description contains frame interval specification, and each
-such specification consists of a number of lines with an inverval value
-in each line. The rules stated above are best illustrated with an example::
-
-  # mkdir functions/uvc.usb0/control/header/h
-  # cd functions/uvc.usb0/control/
-  # ln -s header/h class/fs
-  # ln -s header/h class/ss
-  # mkdir -p functions/uvc.usb0/streaming/uncompressed/u/360p
-  # cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/dwFrameInterval
-  666666
-  1000000
-  5000000
-  EOF
-  # cd $GADGET_CONFIGFS_ROOT
-  # mkdir functions/uvc.usb0/streaming/header/h
-  # cd functions/uvc.usb0/streaming/header/h
-  # ln -s ../../uncompressed/u
-  # cd ../../class/fs
-  # ln -s ../../header/h
-  # cd ../../class/hs
-  # ln -s ../../header/h
-  # cd ../../class/ss
-  # ln -s ../../header/h
-
-
-Testing the UVC function
-------------------------
-
-device: run the gadget, modprobe vivid::
-
-  # uvc-gadget -u /dev/video<uvc video node #> -v /dev/video<vivid video node #>
-
-where uvc-gadget is this program:
-	http://git.ideasonboard.org/uvc-gadget.git
-
-with these patches:
-
-	http://www.spinics.net/lists/linux-usb/msg99220.html
-
-host::
-
-	luvcview -f yuv
-
-19. PRINTER function
-====================
-
-The function is provided by usb_f_printer.ko module.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "printer".
-The printer function provides these attributes in its function directory:
-
-	==========	===========================================
-	pnp_string	Data to be passed to the host in pnp string
-	q_len		Number of requests per endpoint
-	==========	===========================================
-
-Testing the PRINTER function
-----------------------------
-
-The most basic testing:
-
-device: run the gadget::
-
-	# ls -l /devices/virtual/usb_printer_gadget/
-
-should show g_printer<number>.
-
-If udev is active, then /dev/g_printer<number> should appear automatically.
-
-host:
-
-If udev is active, then e.g. /dev/usb/lp0 should appear.
-
-host->device transmission:
-
-device::
-
-	# cat /dev/g_printer<number>
-
-host::
-
-	# cat > /dev/usb/lp0
-
-device->host transmission::
-
-	# cat > /dev/g_printer<number>
-
-host::
-
-	# cat /dev/usb/lp0
-
-More advanced testing can be done with the prn_example
-described in Documentation/usb/gadget_printer.txt.
-
-
-20. UAC1 function (virtual ALSA card, using u_audio API)
-========================================================
-
-The function is provided by usb_f_uac1.ko module.
-It will create a virtual ALSA card and the audio streams are simply
-sinked to and sourced from it.
-
-Function-specific configfs interface
-------------------------------------
-
-The function name to use when creating the function directory is "uac1".
-The uac1 function provides these attributes in its function directory:
-
-	========== ====================================================
-	c_chmask   capture channel mask
-	c_srate    capture sampling rate
-	c_ssize    capture sample size (bytes)
-	p_chmask   playback channel mask
-	p_srate    playback sampling rate
-	p_ssize    playback sample size (bytes)
-	req_number the number of pre-allocated request for both capture
-		   and playback
-	========== ====================================================
-
-The attributes have sane default values.
-
-Testing the UAC1 function
--------------------------
-
-device: run the gadget
-host: aplay -l # should list our USB Audio Gadget
-
-This function does not require real hardware support, it just
-sends a stream of audio data to/from the host. In order to
-actually hear something at the device side, a command similar
-to this must be used at the device side::
-
-	$ arecord -f dat -t wav -D hw:2,0 | aplay -D hw:0,0 &
-
-e.g.::
-
-	$ arecord -f dat -t wav -D hw:CARD=UAC1Gadget,DEV=0 | \
-	  aplay -D default:CARD=OdroidU3