EHCI Gadget Debug
This page is about using embedded GNU/Linux devices in order to get the USB debug logs.
Download the patches that maintain TTY connected while debug target power-cycles or when host controller is reset.
Apply the patches from one of the v3.8- or v3.10-debug-gadget directories on your kernel build tree.
- You need to be familiar with (cross) compiling your kernel.
- (Cross) compile it as usual but during the configuration do the following:
Go into Device Drivers:
Device Drivers --->
Then go into USB support:
[*] USB support --->
Then go into USB Gadget Support:
<M> USB Gadget Support --->
Then enable the following option:
<M> EHCI Debug Device Gadget
Then select the serial option:
EHCI Debug Device mode (serial) --->
Remove all usb gadget drivers such as g_ehter or g_mass_storage with rmmod then do:
I recommend to open the TTY before starting debug target. Doing it the other way around slows down the debug target boot and seems to confuse serial gadget framework.
You may want to disable some CR/LF translations on the device:
stty -icrnl -inlcr -F /dev/ttyGS0
You can directly open the device node, possibly redirecting to file:
.. or use a terminal client:
picocom -ir /dev/ttyGS0
Finding the USB debug port
|Brand and Device||kernel used||Target devices||works?|
|Goldelico GTA04 A3||neil-plus kernel and branch (3.7)||Lenovo X60||Yes|
|Buglabs's bug 2.0||bug20-2.6.35-linaro's master (2.6.35)||Lenovo X60||Yes|