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Documentation: usb: MIDI function testing

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Summary of how to test MIDI function of USB gadget.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
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Andrzej Pietrasiewicz 2014-12-16 14:56:33 +01:00 committed by Felipe Balbi
parent cdbe287d27
commit 0d6be59a1d
1 changed files with 84 additions and 0 deletions
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Documentation/usb/gadget-testing.txt
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@ -9,6 +9,7 @@ provided by gadgets.
6. HID function 6. HID function
7. LOOPBACK function 7. LOOPBACK function
8. MASS STORAGE function 8. MASS STORAGE function
9. MIDI function
1. ACM function 1. ACM function
@ -282,3 +283,86 @@ Testing the MASS STORAGE function
device: connect the gadget, enable it device: connect the gadget, enable it
host: dmesg, see the USB drives appear (if system configured to automatically host: dmesg, see the USB drives appear (if system configured to automatically
mount) 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.