W dniu 13.03.2015 o 12:25, Andrzej Pietrasiewicz pisze:
Hi Wojciech,
W dniu 13.03.2015 o 12:05, Wojciech Zając pisze:
Hello,
I was trying to create FunctionFS based, WinUSB gadget driver on EBV
SoCrates board (Altera Cyclone V SoC, dwc2 UDC), running 4.0-rc3
Kernel, but this attempt ultimately failed with 'Oops'.
<snip>
I wrote my own application for FunctionFS handling, starting with the
same set of descriptors (with minor changes to EP types, etc.).
This also worked as expected, but adding MS OS descriptors (using
functionfs.h structures) afterwards, did not.
Descriptors are accepted on ep0 write, but binding UDC causes the following:
[ 563.185116] ffs_do_os_descs()
[ 563.185122] ffs_do_single_os_desc()
[ 563.185137] Unable to handle kernel paging request at virtual
address 00ffff02
It might be a bug. That said, please see below.
<snip>
I am not sure if this approach is a correct way of using OS
descriptors (what about MS string descriptor?) with FunctionFS
You should set the contents of MS OS string descriptor and enable it.
Here is what you can find in Documentation/ABI/testing/configfs-usb-gadget:
What: /config/usb-gadget/gadget/os_desc
Date: May 2014
KernelVersion: 3.16
Description:
This group contains "OS String" extension handling attributes.
use - flag turning "OS Desctiptors" support on/off
b_vendor_code - one-byte value used for custom per-device and
per-interface requests
qw_sign - an identifier to be reported as "OS String"
proper
You should also link your gadget configuration to be used with OS descriptors
into the os_desc directory, something on the lines of:
# ln -s configs/c.1 os_desc
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