[rt2x00-users] rt2800pci & hw crypto

Ivo Van Doorn ivdoorn at gmail.com
Mon May 31 14:10:09 UTC 2010


Hi,

> I saw you also merged a patch to enable hw crypto by default on rt2800pci.

Well it isn't merged into master. I keep it in my experimental tree for now.
I managed to get some devices working on it with the WPA/WPA2 network,
but only once, (During a second test, none of the devices could
connect to the AP).

However performance was a bit low, since I experience "hickups",
at some moments, packets weren't being send out, but hold for a number
of seconds
before bursting out of the device.

With ping this meant that the response time could sometimes increase
to 5 seconds,
where in some cases the ping failed because the queue was flooded. When normal
operation restored ping response time reduced to a couple of milliseconds.

I still have to test on a WEP network though.

> The patch doesn't break anything but unfortunately it seems that hw crypto
> doesn't work for received frames (only tried rt3052 SoC as usual) and
> mac80211 decrypts them in sw.

Actually I didn't test that part yet. So I can't confirm the same for
the rt2770 devices.

> So, I agree that we can simply turn hwcrypto on by default as it seems that
> encrypting tx frames works just fine but we still have to investigate why
> rx decryption fails.

Well the reason why it defaulted to off, was that it simply didn't work before.
It can be switched to on, if we can have a connection and transfer
data. Which is the
case apparently, since mac80211 can SW decrypt frames anyway...

> Btw. I checked if rx decryption works by printing out RXD_W3_DECRYPTED for every
> rx frame and it was never set :(

I'll test that out for the rt2770 devices, and see if WEP is also working.

If that is the case, I'll submit the patch for merger into the master branch.

Ivo



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