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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
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.