mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-15 15:26:41 +07:00
d80b5005c5
Convert USB documents to ReST, in order to prepare for adding it to the kernel API book, as most of the stuff there are driver or subsystem-related. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
935 lines
26 KiB
Plaintext
935 lines
26 KiB
Plaintext
==============
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Gadget Testing
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==============
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This file summarizes information on basic testing of USB functions
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provided by gadgets.
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.. contents
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1. ACM function
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2. ECM function
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3. ECM subset function
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4. EEM function
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5. FFS function
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6. HID function
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7. LOOPBACK function
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8. MASS STORAGE function
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9. MIDI function
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10. NCM function
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11. OBEX function
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12. PHONET function
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13. RNDIS function
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14. SERIAL function
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15. SOURCESINK function
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16. UAC1 function (legacy implementation)
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17. UAC2 function
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18. UVC function
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19. PRINTER function
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20. UAC1 function (new API)
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1. ACM function
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===============
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The function is provided by usb_f_acm.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "acm".
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The ACM function provides just one attribute in its function directory:
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port_num
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The attribute is read-only.
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There can be at most 4 ACM/generic serial/OBEX ports in the system.
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Testing the ACM function
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------------------------
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On the host::
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cat > /dev/ttyACM<X>
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On the device::
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cat /dev/ttyGS<Y>
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then the other way round
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On the device::
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cat > /dev/ttyGS<Y>
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On the host::
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cat /dev/ttyACM<X>
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2. ECM function
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===============
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The function is provided by usb_f_ecm.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "ecm".
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The ECM function provides these attributes in its function directory:
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=============== ==================================================
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ifname network device interface name associated with this
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function instance
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qmult queue length multiplier for high and super speed
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host_addr MAC address of host's end of this
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Ethernet over USB link
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dev_addr MAC address of device's end of this
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Ethernet over USB link
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=============== ==================================================
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and after creating the functions/ecm.<instance name> they contain default
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values: qmult is 5, dev_addr and host_addr are randomly selected.
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Except for ifname they can be written to until the function is linked to a
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configuration. The ifname is read-only and contains the name of the interface
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which was assigned by the net core, e. g. usb0.
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Testing the ECM function
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------------------------
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Configure IP addresses of the device and the host. Then:
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On the device::
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ping <host's IP>
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On the host::
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ping <device's IP>
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3. ECM subset function
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======================
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The function is provided by usb_f_ecm_subset.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "geth".
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The ECM subset function provides these attributes in its function directory:
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=============== ==================================================
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ifname network device interface name associated with this
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function instance
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qmult queue length multiplier for high and super speed
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host_addr MAC address of host's end of this
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Ethernet over USB link
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dev_addr MAC address of device's end of this
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Ethernet over USB link
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=============== ==================================================
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and after creating the functions/ecm.<instance name> they contain default
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values: qmult is 5, dev_addr and host_addr are randomly selected.
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Except for ifname they can be written to until the function is linked to a
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configuration. The ifname is read-only and contains the name of the interface
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which was assigned by the net core, e. g. usb0.
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Testing the ECM subset function
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-------------------------------
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Configure IP addresses of the device and the host. Then:
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On the device::
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ping <host's IP>
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On the host::
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ping <device's IP>
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4. EEM function
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===============
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The function is provided by usb_f_eem.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "eem".
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The EEM function provides these attributes in its function directory:
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=============== ==================================================
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ifname network device interface name associated with this
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function instance
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qmult queue length multiplier for high and super speed
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host_addr MAC address of host's end of this
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Ethernet over USB link
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dev_addr MAC address of device's end of this
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Ethernet over USB link
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=============== ==================================================
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and after creating the functions/eem.<instance name> they contain default
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values: qmult is 5, dev_addr and host_addr are randomly selected.
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Except for ifname they can be written to until the function is linked to a
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configuration. The ifname is read-only and contains the name of the interface
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which was assigned by the net core, e. g. usb0.
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Testing the EEM function
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------------------------
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Configure IP addresses of the device and the host. Then:
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On the device::
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ping <host's IP>
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On the host::
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ping <device's IP>
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5. FFS function
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===============
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The function is provided by usb_f_fs.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "ffs".
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The function directory is intentionally empty and not modifiable.
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After creating the directory there is a new instance (a "device") of FunctionFS
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available in the system. Once a "device" is available, the user should follow
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the standard procedure for using FunctionFS (mount it, run the userspace
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process which implements the function proper). The gadget should be enabled
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by writing a suitable string to usb_gadget/<gadget>/UDC.
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Testing the FFS function
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------------------------
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On the device: start the function's userspace daemon, enable the gadget
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On the host: use the USB function provided by the device
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6. HID function
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===============
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The function is provided by usb_f_hid.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "hid".
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The HID function provides these attributes in its function directory:
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=============== ===========================================
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protocol HID protocol to use
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report_desc data to be used in HID reports, except data
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passed with /dev/hidg<X>
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report_length HID report length
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subclass HID subclass to use
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=============== ===========================================
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For a keyboard the protocol and the subclass are 1, the report_length is 8,
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while the report_desc is::
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$ hd my_report_desc
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00000000 05 01 09 06 a1 01 05 07 19 e0 29 e7 15 00 25 01 |..........)...%.|
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00000010 75 01 95 08 81 02 95 01 75 08 81 03 95 05 75 01 |u.......u.....u.|
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00000020 05 08 19 01 29 05 91 02 95 01 75 03 91 03 95 06 |....).....u.....|
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00000030 75 08 15 00 25 65 05 07 19 00 29 65 81 00 c0 |u...%e....)e...|
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0000003f
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Such a sequence of bytes can be stored to the attribute with echo::
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$ echo -ne \\x05\\x01\\x09\\x06\\xa1.....
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Testing the HID function
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------------------------
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Device:
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- create the gadget
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- connect the gadget to a host, preferably not the one used
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to control the gadget
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- run a program which writes to /dev/hidg<N>, e.g.
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a userspace program found in Documentation/usb/gadget_hid.txt::
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$ ./hid_gadget_test /dev/hidg0 keyboard
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Host:
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- observe the keystrokes from the gadget
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7. LOOPBACK function
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====================
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The function is provided by usb_f_ss_lb.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "Loopback".
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The LOOPBACK function provides these attributes in its function directory:
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=============== =======================
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qlen depth of loopback queue
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bulk_buflen buffer length
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=============== =======================
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Testing the LOOPBACK function
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-----------------------------
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device: run the gadget
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host: test-usb (tools/usb/testusb.c)
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8. MASS STORAGE function
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========================
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The function is provided by usb_f_mass_storage.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "mass_storage".
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The MASS STORAGE function provides these attributes in its directory:
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files:
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=============== ==============================================
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stall Set to permit function to halt bulk endpoints.
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Disabled on some USB devices known not to work
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correctly. You should set it to true.
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num_buffers Number of pipeline buffers. Valid numbers
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are 2..4. Available only if
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CONFIG_USB_GADGET_DEBUG_FILES is set.
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=============== ==============================================
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and a default lun.0 directory corresponding to SCSI LUN #0.
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A new lun can be added with mkdir::
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$ mkdir functions/mass_storage.0/partition.5
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Lun numbering does not have to be continuous, except for lun #0 which is
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created by default. A maximum of 8 luns can be specified and they all must be
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named following the <name>.<number> scheme. The numbers can be 0..8.
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Probably a good convention is to name the luns "lun.<number>",
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although it is not mandatory.
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In each lun directory there are the following attribute files:
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=============== ==============================================
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file The path to the backing file for the LUN.
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Required if LUN is not marked as removable.
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ro Flag specifying access to the LUN shall be
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read-only. This is implied if CD-ROM emulation
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is enabled as well as when it was impossible
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to open "filename" in R/W mode.
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removable Flag specifying that LUN shall be indicated as
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being removable.
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cdrom Flag specifying that LUN shall be reported as
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being a CD-ROM.
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nofua Flag specifying that FUA flag
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in SCSI WRITE(10,12)
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=============== ==============================================
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Testing the MASS STORAGE function
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---------------------------------
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device: connect the gadget, enable it
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host: dmesg, see the USB drives appear (if system configured to automatically
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mount)
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9. MIDI function
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================
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The function is provided by usb_f_midi.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "midi".
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The MIDI function provides these attributes in its function directory:
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=============== ====================================
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buflen MIDI buffer length
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id ID string for the USB MIDI adapter
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in_ports number of MIDI input ports
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index index value for the USB MIDI adapter
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out_ports number of MIDI output ports
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qlen USB read request queue length
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=============== ====================================
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Testing the MIDI function
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-------------------------
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There are two cases: playing a mid from the gadget to
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the host and playing a mid from the host to the gadget.
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1) Playing a mid from the gadget to the host:
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host::
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$ arecordmidi -l
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Port Client name Port name
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14:0 Midi Through Midi Through Port-0
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24:0 MIDI Gadget MIDI Gadget MIDI 1
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$ arecordmidi -p 24:0 from_gadget.mid
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gadget::
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$ aplaymidi -l
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Port Client name Port name
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20:0 f_midi f_midi
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$ aplaymidi -p 20:0 to_host.mid
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2) Playing a mid from the host to the gadget
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gadget::
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$ arecordmidi -l
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Port Client name Port name
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20:0 f_midi f_midi
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$ arecordmidi -p 20:0 from_host.mid
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host::
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$ aplaymidi -l
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Port Client name Port name
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14:0 Midi Through Midi Through Port-0
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24:0 MIDI Gadget MIDI Gadget MIDI 1
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$ aplaymidi -p24:0 to_gadget.mid
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The from_gadget.mid should sound identical to the to_host.mid.
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The from_host.id should sound identical to the to_gadget.mid.
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MIDI files can be played to speakers/headphones with e.g. timidity installed::
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$ aplaymidi -l
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Port Client name Port name
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14:0 Midi Through Midi Through Port-0
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24:0 MIDI Gadget MIDI Gadget MIDI 1
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128:0 TiMidity TiMidity port 0
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128:1 TiMidity TiMidity port 1
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128:2 TiMidity TiMidity port 2
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128:3 TiMidity TiMidity port 3
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$ aplaymidi -p 128:0 file.mid
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MIDI ports can be logically connected using the aconnect utility, e.g.::
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$ aconnect 24:0 128:0 # try it on the host
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After the gadget's MIDI port is connected to timidity's MIDI port,
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whatever is played at the gadget side with aplaymidi -l is audible
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in host's speakers/headphones.
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10. NCM function
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================
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The function is provided by usb_f_ncm.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "ncm".
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The NCM function provides these attributes in its function directory:
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=============== ==================================================
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ifname network device interface name associated with this
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function instance
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qmult queue length multiplier for high and super speed
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host_addr MAC address of host's end of this
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Ethernet over USB link
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dev_addr MAC address of device's end of this
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Ethernet over USB link
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=============== ==================================================
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and after creating the functions/ncm.<instance name> they contain default
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values: qmult is 5, dev_addr and host_addr are randomly selected.
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Except for ifname they can be written to until the function is linked to a
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configuration. The ifname is read-only and contains the name of the interface
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which was assigned by the net core, e. g. usb0.
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Testing the NCM function
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------------------------
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Configure IP addresses of the device and the host. Then:
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On the device::
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ping <host's IP>
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On the host::
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ping <device's IP>
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11. OBEX function
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=================
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The function is provided by usb_f_obex.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "obex".
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The OBEX function provides just one attribute in its function directory:
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port_num
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The attribute is read-only.
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There can be at most 4 ACM/generic serial/OBEX ports in the system.
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Testing the OBEX function
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-------------------------
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On device::
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seriald -f /dev/ttyGS<Y> -s 1024
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On host::
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serialc -v <vendorID> -p <productID> -i<interface#> -a1 -s1024 \
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-t<out endpoint addr> -r<in endpoint addr>
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where seriald and serialc are Felipe's utilities found here:
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https://github.com/felipebalbi/usb-tools.git master
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12. PHONET function
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===================
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The function is provided by usb_f_phonet.ko module.
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Function-specific configfs interface
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------------------------------------
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The function name to use when creating the function directory is "phonet".
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The PHONET function provides just one attribute in its function directory:
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=============== ==================================================
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ifname network device interface name associated with this
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function instance
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=============== ==================================================
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Testing the PHONET function
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---------------------------
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It is not possible to test the SOCK_STREAM protocol without a specific piece
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of hardware, so only SOCK_DGRAM has been tested. For the latter to work,
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in the past I had to apply the patch mentioned here:
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http://www.spinics.net/lists/linux-usb/msg85689.html
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These tools are required:
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git://git.gitorious.org/meego-cellular/phonet-utils.git
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On the host::
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$ ./phonet -a 0x10 -i usbpn0
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$ ./pnroute add 0x6c usbpn0
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$./pnroute add 0x10 usbpn0
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$ ifconfig usbpn0 up
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On the device::
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$ ./phonet -a 0x6c -i upnlink0
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$ ./pnroute add 0x10 upnlink0
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$ ifconfig upnlink0 up
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Then a test program can be used::
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http://www.spinics.net/lists/linux-usb/msg85690.html
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On the device::
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$ ./pnxmit -a 0x6c -r
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On the host::
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$ ./pnxmit -a 0x10 -s 0x6c
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As a result some data should be sent from host to device.
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Then the other way round:
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On the host::
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$ ./pnxmit -a 0x10 -r
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On the device::
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$ ./pnxmit -a 0x6c -s 0x10
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13. RNDIS function
|
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==================
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|
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The function is provided by usb_f_rndis.ko module.
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|
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Function-specific configfs interface
|
|
------------------------------------
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The function name to use when creating the function directory is "rndis".
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The RNDIS function provides these attributes in its function directory:
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|
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=============== ==================================================
|
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ifname network device interface name associated with this
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function instance
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qmult queue length multiplier for high and super speed
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host_addr MAC address of host's end of this
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Ethernet over USB link
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dev_addr MAC address of device's end of this
|
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Ethernet over USB link
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=============== ==================================================
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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
|