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Documentation: usb: UVC function testing

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Summary of how to test UVC 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 14:56:42 +01:00 committed by Felipe Balbi
parent 020c6f9348
commit 9c4f538bfa
1 changed files with 73 additions and 0 deletions
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73
Documentation/usb/gadget-testing.txt
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@ -18,6 +18,7 @@ provided by gadgets.
15. SOURCESINK function
16. UAC1 function
17. UAC2 function
18. UVC function
1. ACM function
@ -653,3 +654,75 @@ e.g.:
$ arecord -f dat -t wav -D hw:CARD=UAC2Gadget,DEV=0 | \
aplay -D default:CARD=OdroidU3
18. UVC function
================
The function is provided by usb_f_uvc.ko module.
Function-specific configfs interface
------------------------------------
The function name to use when creating the function directory is "uvc".
The uvc function provides these attributes in its function directory:
streaming_interval - interval for polling endpoint for data transfers
streaming_maxburst - bMaxBurst for super speed companion descriptor
streaming_maxpacket - maximum packet size this endpoint is capable of
sending or receiving when this configuration is
selected
There are also "control" and "streaming" subdirectories, each of which contain
a number of their subdirectories. There are some sane defaults provided, but
the user must provide the following:
control header - create in control/header, link from control/class/fs
and/or control/class/ss
streaming header - create in streaming/header, link from
streaming/class/fs and/or streaming/class/hs and/or
streaming/class/ss
format description - create in streaming/mjpeg and/or
streaming/uncompressed
frame description - create in streaming/mjpeg/<format> and/or in
streaming/uncompressed/<format>
Each frame description contains frame interval specification, and each
such specification consists of a number of lines with an inverval value
in each line. The rules stated above are best illustrated with an example:
# mkdir functions/uvc.usb0/control/header/h
# cd functions/uvc.usb0/control/header/h
# ln -s header/h class/fs
# ln -s header/h class/ss
# mkdir -p functions/uvc.usb0/streaming/uncompressed/u/360p
# cat <<EOF > functions/uvc.usb0/streaming/uncompressed/u/360p/dwFrameInterval
666666
1000000
5000000
EOF
# cd $GADGET_CONFIGFS_ROOT
# mkdir functions/uvc.usb0/streaming/header/h
# cd functions/uvc.usb0/streaming/header/h
# ln -s ../../uncompressed/u
# cd ../../class/fs
# ln -s ../../header/h
# cd ../../class/hs
# ln -s ../../header/h
# cd ../../class/ss
# ln -s ../../header/h
Testing the UVC function
------------------------
device: run the gadget, modprobe vivid
# uvc-gadget -u /dev/video<uvc video node #> -v /dev/video<vivid video node #>
where uvc-gadget is this program:
http://git.ideasonboard.org/uvc-gadget.git
with these patches:
http://www.spinics.net/lists/linux-usb/msg99220.html
host: luvcview -f yuv