Bruno_F 
I'm currently trying to make the USB Wi-Fi adapter TL-WN321G (from TP-Link)
work under the 2.6.38 Linux Kernel (linux-2.6.38-20110325.tar.gz from the
DVD images), but I'm having no success. Plus, I'm no Linux wizard, and the
best I did until now was tweaking the kernel to access GPIO through the
sysfs (/sys/class/gpio/ folder), and created programs that can handle GPIO
outputs, get ADC readings and manage the PWM (all in C).
Before make'n the kernel, on the configuration menu I added:
[*] Networking support --->
-*- Wireless --->
[*] Wireless extensions sysfs files
-*- Common routines for IEEE802.11 drivers
Device Drivers --->
[*] Staging Drivers --->
[ ] Exclude Staging drivers from being built
<*> Ralink 2870/3070 wireless support
After doing so, when I use "iwconfig" on the terminal, it shows the "wlan0"
corresponding to the adapter, but whenever I try "ifconfig wlan0 up", it
hangs for some time, and then show up the error "ifconfig: SIOCSIFFLAGS:
Operation not permitted".
Before doing this, I tried to follow this guide
(http://embedded.abstract-blue.net/?p=14#more-14), although I wasn't able
to compile the right .ko file (not knowing why). When checking the kernel
configuration menu I found the "Ralink 2870/3070 wireless support" and
thought that the problem was resolved, even more when the wlan0 showed up
(after connecting the device).
Everywhere I look up, I teaches how to install the drivers by hand, or the
wpa_supplicant. This don't make a lot of sense for me, since the
wpa_supplicant is already present on this build (using "wpa_supplicant" on
the terminal shows the "how-to-use"), and the drivers are already installed
beforehand.
I also tried the kernel config above with the 2.6.36, with the same
results.
Am I missing something silly?