[rt2x00-users] rt2800pci works nearly fine with 2.6.39rc7 kernel and compat-wireless-2.6.39-rc6-1 - problems during rekeying of PTK

[Helmut Schaa]

Am Dienstag, 31. Mai 2011 schrieb Johannes Stezenbach:
> On Tue, May 31, 2011 at 03:39:03PM +0200, Helmut Schaa wrote:
> > Am Dienstag, 31. Mai 2011 schrieb Johannes Stezenbach:
> > 
> > > Maybe this could explain why EAPOL fails while data frames
> > > can still be exchanged? If debug were enabled the driver would
> > > log the missing TX status, but the queue would not get completely
> > > stuck, right?
> > 
> > No, rt2800pci currently doesn't use the watchdog and hence won't detect
> > lost tx status reports. I once started to write a watchdog but never finished
> > it since I could't make it fail any reports anymore.
> > 
> > But without further investigation I tend to believe that no tx status
> > is lost but the frames are just not transmitted in time (for whatever reason),
> > but that is only a gut feeling.
> 
> I thought we would detect missing TX status without watchdog
> based on TXWI_W1_PACKETID_ENTRY vs. TX_STA_FIFO_PID_ENTRY?

Sort of, yes. However, as soon as aggregation is involved everything changes :(

Assume the following frames queued on the same tx queue:

PID_ENTRY 0,1,2

If the hw sends out an AMPDU containing all three frames the PID_ENTRY field
in the tx status report looks like

PID_ENTRY 0,0,0

because the hw always reports the PID field of the first frame of an AMPDU
as PID field for all following frames in the same AMPDU.

So, this is not 100% reliable as well.

Helmut