| ============== |
| 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. |
| The ifname can be written to if the function is not bound. A write must be an |
| interface pattern such as "usb%d", which will cause the net core to choose the |
| next free usbX interface. By default, it is set to "usb%d". |
| |
| 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. |
| The ifname can be written to if the function is not bound. A write must be an |
| interface pattern such as "usb%d", which will cause the net core to choose the |
| next free usbX interface. By default, it is set to "usb%d". |
| |
| 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. |
| The ifname can be written to if the function is not bound. A write must be an |
| interface pattern such as "usb%d", which will cause the net core to choose the |
| next free usbX interface. By default, it is set to "usb%d". |
| |
| 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.rst:: |
| |
| $ ./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. |
| The ifname can be written to if the function is not bound. A write must be an |
| interface pattern such as "usb%d", which will cause the net core to choose the |
| next free usbX interface. By default, it is set to "usb%d". |
| |
| 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. |
| The ifname can be written to if the function is not bound. A write must be an |
| interface pattern such as "usb%d", which will cause the net core to choose the |
| next free usbX interface. By default, it is set to "usb%d". |
| |
| 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) |
| c_sync capture synchronization type (async/adaptive) |
| c_mute_present capture mute control enable |
| c_volume_present capture volume control enable |
| c_volume_min capture volume control min value (in 1/256 dB) |
| c_volume_max capture volume control max value (in 1/256 dB) |
| c_volume_res capture volume control resolution (in 1/256 dB) |
| fb_max maximum extra bandwidth in async mode |
| p_chmask playback channel mask |
| p_srate playback sampling rate |
| p_ssize playback sample size (bytes) |
| p_mute_present playback mute control enable |
| p_volume_present playback volume control enable |
| p_volume_min playback volume control min value (in 1/256 dB) |
| p_volume_max playback volume control max value (in 1/256 dB) |
| p_volume_res playback volume control resolution (in 1/256 dB) |
| 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.rst. |
| |
| |
| 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) |
| c_mute_present capture mute control enable |
| c_volume_present capture volume control enable |
| c_volume_min capture volume control min value (in 1/256 dB) |
| c_volume_max capture volume control max value (in 1/256 dB) |
| c_volume_res capture volume control resolution (in 1/256 dB) |
| p_chmask playback channel mask |
| p_srate playback sampling rate |
| p_ssize playback sample size (bytes) |
| p_mute_present playback mute control enable |
| p_volume_present playback volume control enable |
| p_volume_min playback volume control min value (in 1/256 dB) |
| p_volume_max playback volume control max value (in 1/256 dB) |
| p_volume_res playback volume control resolution (in 1/256 dB) |
| req_number the number of pre-allocated requests 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 |
