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ath5k driver on MIPS and low level control over the hw

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Hello everybody,

I have been following the ath5k project for a while hoping that the new driver could sort out the speed issue that afflicts the MIPS platform I am using: I'm involved in a performance evaluation task and I need to hack the kernel in such a way that frames are created from a task running in kernel space and sent directly to the device without passing through the traditional network stack. Clearly I cannot deal with a closed binary.

After a small effort to have 2.6.24-rc2 booting up and running without problems on my MIPS boards (Mikrotik RB133), I finally added the ath5k driver and everything went fine: the driver is usable also on these MIPS boards, wlan0 network is up and everything work, I can join a test network without using encryption, still have not tested with WEP.

I did some tests and I see that setting up filters properly I can also see ACKs, RTSs and all other stuff.

I have now a few questions

- is it possible to (e.g. does anybody ever succeeded to) ask the hw to transmit a skb-encoded frame with arbitrary content? I mean, is it possible to disable CSMA/CA mechanism, call ath5k_txbuf_setup() and let the hw to not check if a frame is actually received by someone? - how is it implemented the rate control in the ath5k driver? I see that if a force 54M rate and the channel does not allow (e.g. noise due to other BSs in the same channel) this rate the driver takes a long time to switch to a lower rate (and usually it switches to 1Mb/s) - I'm not using the wireless git branch but the standard development 2.6.24-rc2 code with ath5k added in driver/net/wireless: I suppose that this is ok because I have no problems with the net/mac80211 part coming with the standard kernel but if someone is aware of changes in this part, please let me now.

I would like also to report that I did a very simple test connecting a couple of Atheros card with a coaxial cable (impedances adapted and both systems are connected to the same ground). The two PCs involved are running x86 Linux 2.6.24-rc2 when using ath5k and Linux 2.6.23 when using standard Madwifi code. I see that independently of the channel rate (from 1Mb/s to 54Mb/s) I always get better performances with standard Madwifi code. Could this depend on how queues are handled on the ath5k code?

Regards,
FG

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Francesco Gringoli, PhD - Assistant Professor
Dept. of Electrical Engineering for Automation
University of Brescia
via Branze, 38
25123 Brescia
ITALY

Ph:  ++39.030.3715843
FAX: ++39.030.380014

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