Re: tx_status reporting of RTS/CTS frames

[Jouni Malinen <j@w1.fi>]

On Wed, Dec 12, 2007 at 06:15:02PM +0100, Johannes Berg wrote:

> > rt2x00 devices can't generate rts/cts frames themselves, but rely on the
> > driver to generate them. Also, the hardware reports tx status back for
> > those frames. Now the question is whether these frames should be
> > reported back to mac80211 using ieee80211_tx_status[_irqsafe]. AFAIK,
> > this has some subtle effects, e.g. they won't show up on monitor
> > interfaces if we don't report them.
> 
> They never show up on monitor interfaces for all other hardware because
> there the hardware handles them. How is it that rt2x00 cannot handle
> rts? It has to at least know that an RTS was sent and to send the frame
> only after the CTS, and that needs to be a MAC function and cannot be
> implemented in host software.
> 
> So, I'd think they shouldn't be reported at all.

I'm not sure I understood the comment about monitor interface correctly.
If the driver is configured in monitor mode (or whatever you would call
a mode where it receives all frames), I do expect to see ACK and RTS/CTS
frames in mac80211 (and in the monitor interface in user space for that
matter). I hope that this won't be changed.

It sounds perfectly reasonable to not indicate these control frame
subtypes when in normal (non-monitor) mode since they are most likely
processed in hardware/microcode/firmware. However, if they provide
additional information (say, signal strength), it could be useful to
send them to mac80211 anyway to provide more information for TX rate
control.

-- 
Jouni Malinen                                            PGP id EFC895FA