USB adapter firmware: 1.8.x generates lots of TX EXC events?

Chris Rankin rankincj
Sat Jun 11 13:22:23 PDT 2005


I've noticed that linux-wlan-ng's prism2_usb driver has great difficulty talking to a hostap AP
device, whenver the USB adapter is running firmware 1.8.x. The reason for this seems to be that
the AP receives lots of TX EXC frames from the adapter, which the AP then responds to by lowering
the bit rate. (More precisely, the hostap_sta_tx_exc_tasklet() function is invoked heavily when
receiving frames from a 1.8.x USB adapter, and hardly ever when the adapter runs <= 1.7.6.)

I remember that there is line of code in prism2_usb's hfa384x_drvr_txframe() function:

        txdesc.tx_control =
                HFA384x_TX_MACPORT_SET(0) | HFA384x_TX_STRUCTYPE_SET(1) |
                HFA384x_TX_TXEX_SET(0) | HFA384x_TX_TXOK_SET(0);

However, this says that we are already NOT transmitting either TXEX and TXOK frames. And IIRC, the
adapter will lock up if we do enable them. So can anyone explain what firmware 1.8.x might be
doing to trigger hostap's tx_exc tasklet, please?

Also, does anyone have a RAM version of USB station firmware 1.8.4? I would like to test this
version before flashing it.


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