Hi all,

to learn about the in kernel 802.11 subsystem, driver writing and wireless in 
general, I started a project to develop a driver for the prism2/prism3 usb 
chipset. Goal was to get WPA support and the possibility to configure with 
wireless extensions.

Unfortunately, I was rudely interrupted when I toasted my only card by 
downgrading from secondary firmware 1.8.4 to 1.7.4. The latest state of my 
work is available at  http://80.237.161.167/prism2_usb-incomplete.tar.bz2 . 
It can scan, associate to an unencrypted network and transmit data, I've 
started WPA support. It still has issues with USB timing (unbelievable how 
easily this device gets into an unresponsive state), incomplete USB device 
list and is of course far away from finished. But if someone is brave enough 
to continue, feel free to download and contact me directly if you have 
questions. You need at least firmware 1.7.0, I developed against kernel 
2.6.14.4.

My experiences with the 'intel' 802.11 subsystem are these: It seems to be 
quite usable for drivers that have their own firmware for scanning and 
associating. I've stumbled over the following limitations:

-There needs to be a general function to select the best network. This is code 
copied into neary every device driver, but hard to do it right.
-Fragmentation is solved very uglily. A list of all fragments of a packet is 
submitted to the driver at once. If it doesn't have enough TX descriptors / 
URBs or whatever, the driver has to keep it's own list of fragments. This 
should be abstracted
-Especially USB devices need to send an URB that contains commands in the 
beginning, followed by the 802.11 frame. To support this without excessive 
memcpy()ing, I would have liked a variable in struct ieee80211_device that 
instructs how many bytes of a SKB should be left empty at the beginning.

Ok, don't have anymore hardware to burn, so ... enough for today.

Stefan

PS: Anyone has a spare part he doesn't need? ;-)
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