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Commit 0d6be59a authored by Andrzej Pietrasiewicz's avatar Andrzej Pietrasiewicz Committed by Felipe Balbi
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Documentation: usb: MIDI function testing 



Summary of how to test MIDI function of USB gadget.

Signed-off-by: default avatarAndrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
parent cdbe287d

Documentation/usb/gadget-testing.txt

+84 −0
Original line number Diff line number Diff line
@@ -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.