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Documentation: usb: MASS STORAGE function testing 

Summary of how to test MASS STORAGE function of USB gadget.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
hifive-unleashed-5.1
Andrzej Pietrasiewicz 2014-12-16 14:56:32 +01:00 committed by Felipe Balbi
parent ec91aff763
commit cdbe287d27
1 changed files with 54 additions and 0 deletions
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Documentation/usb/gadget-testing.txt
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@ -8,6 +8,7 @@ provided by gadgets.
5. FFS function
6. HID function
7. LOOPBACK function
8. MASS STORAGE function
1. ACM function
@ -228,3 +229,56 @@ device: run the gadget
host: test-usb
http://www.linux-usb.org/usbtest/testusb.c
8. MASS STORAGE function
========================
The function is provided by usb_f_mass_storage.ko module.
Function-specific configfs interface
------------------------------------
The function name to use when creating the function directory is "mass_storage".
The MASS STORAGE function provides these attributes in its directory:
files:
stall - Set to permit function to halt bulk endpoints.
Disabled on some USB devices known not to work
correctly. You should set it to true.
num_buffers - Number of pipeline buffers. Valid numbers
are 2..4. Available only if
CONFIG_USB_GADGET_DEBUG_FILES is set.
and a default lun.0 directory corresponding to SCSI LUN #0.
A new lun can be added with mkdir:
$ mkdir functions/mass_storage.0/partition.5
Lun numbering does not have to be continuous, except for lun #0 which is
created by default. A maximum of 8 luns can be specified and they all must be
named following the <name>.<number> scheme. The numbers can be 0..8.
Probably a good convention is to name the luns "lun.<number>",
although it is not mandatory.
In each lun directory there are the following attribute files:
file - The path to the backing file for the LUN.
Required if LUN is not marked as removable.
ro - Flag specifying access to the LUN shall be
read-only. This is implied if CD-ROM emulation
is enabled as well as when it was impossible
to open "filename" in R/W mode.
removable - Flag specifying that LUN shall be indicated as
being removable.
cdrom - Flag specifying that LUN shall be reported as
being a CD-ROM.
nofua - Flag specifying that FUA flag
in SCSI WRITE(10,12)
Testing the MASS STORAGE function
---------------------------------
device: connect the gadget, enable it
host: dmesg, see the USB drives appear (if system configured to automatically
mount)