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967 lines
28 KiB
967 lines
28 KiB
============== |
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Gadget Testing |
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============== |
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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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The ifname can be written to if the function is not bound. A write must be an |
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interface pattern such as "usb%d", which will cause the net core to choose the |
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next free usbX interface. By default, it is set to "usb%d". |
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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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The ifname can be written to if the function is not bound. A write must be an |
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interface pattern such as "usb%d", which will cause the net core to choose the |
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next free usbX interface. By default, it is set to "usb%d". |
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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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The ifname can be written to if the function is not bound. A write must be an |
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interface pattern such as "usb%d", which will cause the net core to choose the |
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next free usbX interface. By default, it is set to "usb%d". |
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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.rst:: |
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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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forced_eject This write-only file is useful only when |
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the function is active. It causes the backing |
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file to be forcibly detached from the LUN, |
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regardless of whether the host has allowed it. |
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Any non-zero number of bytes written will |
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result in ejection. |
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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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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. |
|
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 |
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next free usbX interface. By default, it is set to "usb%d". |
|
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Testing the NCM function |
|
------------------------ |
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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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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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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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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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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 |
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Ethernet over USB link |
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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:: |
|
|
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ping <host's IP> |
|
|
|
On the host:: |
|
|
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ping <device's IP> |
|
|
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14. SERIAL function |
|
=================== |
|
|
|
The function is provided by usb_f_gser.ko module. |
|
|
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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: |
|
|
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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 |
|
--------------------------- |
|
|
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On host:: |
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insmod usbserial |
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echo VID PID >/sys/bus/usb-serial/drivers/generic/new_id |
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On host:: |
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cat > /dev/ttyUSB<X> |
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On target:: |
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cat /dev/ttyGS<Y> |
|
|
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then the other way round |
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On target:: |
|
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cat > /dev/ttyGS<Y> |
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On host:: |
|
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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: |
|
|
|
=============== ================================== |
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pattern 0 (all zeros), 1 (mod63), 2 (none) |
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isoc_interval 1..16 |
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isoc_maxpacket 0 - 1023 (fs), 0 - 1024 (hs/ss) |
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isoc_mult 0..2 (hs/ss only) |
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isoc_maxburst 0..15 (ss only) |
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bulk_buflen buffer length |
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bulk_qlen depth of queue for bulk |
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iso_qlen depth of queue for iso |
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=============== ================================== |
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Testing the SOURCESINK 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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16. UAC1 function (legacy implementation) |
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========================================= |
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The function is provided by usb_f_uac1_legacy.ko module. |
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Function-specific configfs interface |
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------------------------------------ |
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|
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The function name to use when creating the function directory |
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is "uac1_legacy". |
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The uac1 function provides these attributes in its function directory: |
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=============== ==================================== |
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audio_buf_size audio buffer size |
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fn_cap capture pcm device file name |
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fn_cntl control device file name |
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fn_play playback pcm device file name |
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req_buf_size ISO OUT endpoint request buffer size |
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req_count ISO OUT endpoint request count |
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=============== ==================================== |
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The attributes have sane default values. |
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Testing the UAC1 function |
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------------------------- |
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device: run the gadget |
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host:: |
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aplay -l # should list our USB Audio Gadget |
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17. UAC2 function |
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================= |
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The function is provided by usb_f_uac2.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 "uac2". |
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The uac2 function provides these attributes in its function directory: |
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================ ==================================================== |
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c_chmask capture channel mask |
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c_srate list of capture sampling rates (comma-separated) |
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c_ssize capture sample size (bytes) |
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c_sync capture synchronization type (async/adaptive) |
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c_mute_present capture mute control enable |
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c_volume_present capture volume control enable |
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c_volume_min capture volume control min value (in 1/256 dB) |
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c_volume_max capture volume control max value (in 1/256 dB) |
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c_volume_res capture volume control resolution (in 1/256 dB) |
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c_hs_bint capture bInterval for HS/SS (1-4: fixed, 0: auto) |
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fb_max maximum extra bandwidth in async mode |
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p_chmask playback channel mask |
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p_srate list of playback sampling rates (comma-separated) |
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p_ssize playback sample size (bytes) |
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p_mute_present playback mute control enable |
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p_volume_present playback volume control enable |
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p_volume_min playback volume control min value (in 1/256 dB) |
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p_volume_max playback volume control max value (in 1/256 dB) |
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p_volume_res playback volume control resolution (in 1/256 dB) |
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p_hs_bint playback bInterval for HS/SS (1-4: fixed, 0: auto) |
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req_number the number of pre-allocated request for both capture |
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and playback |
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function_name name of the interface |
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================ ==================================================== |
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The attributes have sane default values. |
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Testing the UAC2 function |
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------------------------- |
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device: run the gadget |
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host: aplay -l # should list our USB Audio Gadget |
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This function does not require real hardware support, it just |
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sends a stream of audio data to/from the host. In order to |
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actually hear something at the device side, a command similar |
|
to this must be used at the device side:: |
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|
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$ arecord -f dat -t wav -D hw:2,0 | aplay -D hw:0,0 & |
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e.g.:: |
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$ arecord -f dat -t wav -D hw:CARD=UAC2Gadget,DEV=0 | \ |
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aplay -D default:CARD=OdroidU3 |
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18. UVC function |
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================ |
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The function is provided by usb_f_uvc.ko module. |
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|
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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 "uvc". |
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The uvc function provides these attributes in its function directory: |
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|
=================== ================================================ |
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streaming_interval interval for polling endpoint for data transfers |
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streaming_maxburst bMaxBurst for super speed companion descriptor |
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streaming_maxpacket maximum packet size this endpoint is capable of |
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sending or receiving when this configuration is |
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selected |
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function_name name of the interface |
|
=================== ================================================ |
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There are also "control" and "streaming" subdirectories, each of which contain |
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a number of their subdirectories. There are some sane defaults provided, but |
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the user must provide the following: |
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|
|
================== ==================================================== |
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control header create in control/header, link from control/class/fs |
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and/or control/class/ss |
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streaming header create in streaming/header, link from |
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streaming/class/fs and/or streaming/class/hs and/or |
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streaming/class/ss |
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format description create in streaming/mjpeg and/or |
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streaming/uncompressed |
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frame description create in streaming/mjpeg/<format> and/or in |
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streaming/uncompressed/<format> |
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================== ==================================================== |
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|
Each frame description contains frame interval specification, and each |
|
such specification consists of a number of lines with an inverval value |
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in each line. The rules stated above are best illustrated with an example:: |
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# mkdir functions/uvc.usb0/control/header/h |
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# cd functions/uvc.usb0/control/ |
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# ln -s header/h class/fs |
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# ln -s header/h class/ss |
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# mkdir -p functions/uvc.usb0/streaming/uncompressed/u/360p |
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# cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/dwFrameInterval |
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666666 |
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1000000 |
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5000000 |
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EOF |
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# cd $GADGET_CONFIGFS_ROOT |
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# mkdir functions/uvc.usb0/streaming/header/h |
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# cd functions/uvc.usb0/streaming/header/h |
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# ln -s ../../uncompressed/u |
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# cd ../../class/fs |
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# ln -s ../../header/h |
|
# cd ../../class/hs |
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# ln -s ../../header/h |
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# cd ../../class/ss |
|
# ln -s ../../header/h |
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|
|
Testing the UVC function |
|
------------------------ |
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|
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device: run the gadget, modprobe vivid:: |
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|
|
# uvc-gadget -u /dev/video<uvc video node #> -v /dev/video<vivid video node #> |
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|
|
where uvc-gadget is this program: |
|
http://git.ideasonboard.org/uvc-gadget.git |
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|
|
with these patches: |
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|
|
http://www.spinics.net/lists/linux-usb/msg99220.html |
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|
|
host:: |
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|
|
luvcview -f yuv |
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|
|
19. PRINTER function |
|
==================== |
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|
|
The function is provided by usb_f_printer.ko module. |
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|
|
Function-specific configfs interface |
|
------------------------------------ |
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|
|
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 |
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q_len Number of requests per endpoint |
|
========== =========================================== |
|
|
|
Testing the PRINTER function |
|
---------------------------- |
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|
|
The most basic testing: |
|
|
|
device: run the gadget:: |
|
|
|
# ls -l /devices/virtual/usb_printer_gadget/ |
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|
|
should show g_printer<number>. |
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|
|
If udev is active, then /dev/g_printer<number> should appear automatically. |
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|
|
host: |
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|
|
If udev is active, then e.g. /dev/usb/lp0 should appear. |
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|
|
host->device transmission: |
|
|
|
device:: |
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|
|
# cat /dev/g_printer<number> |
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|
|
host:: |
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|
|
# cat > /dev/usb/lp0 |
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|
|
device->host transmission:: |
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|
|
# cat > /dev/g_printer<number> |
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|
|
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 list of capture sampling rates (comma-separated) |
|
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 list of playback sampling rates (comma-separated) |
|
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 |
|
function_name name of the interface |
|
================ ==================================================== |
|
|
|
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
|
|
|