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| -rw-r--r-- | Documentation/usb/gadget-testing.txt | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/Documentation/usb/gadget-testing.txt b/Documentation/usb/gadget-testing.txt index 01b9ffe2eabc..c2f148d245a5 100644 --- a/Documentation/usb/gadget-testing.txt +++ b/Documentation/usb/gadget-testing.txt @@ -9,6 +9,7 @@ provided by gadgets. 6. HID function 7. LOOPBACK function 8. MASS STORAGE function +9. MIDI function 1. ACM function @@ -282,3 +283,86 @@ 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. |