On Saturday 22 January 2011 04:32:02 Sujith wrote:
> Sujith wrote:
> > Sujith wrote:
> > > What about hardware that doesn't report any kind of TX status information
> > > at all ?
> > > Currently, there is no way to determine whether the frame has actually
> > > gone out,
> > > all that can be known is that it was pushed to the target.
> >
> > Am curious how carl9170 gets the TX status ?
> > Is there a separate endpoint ?
>
> I looked a bit into carl9170 and it looks like the TX status
> is obtained as incoming data through the CMD endpoint, am I correct ?
yes and no ;).
The tx status is obtained from the (RX-) DATA [stream/] endpoint.
The (USB?) CMD endpoint is only being used for fatal 0xc6
watchdog events [which are generated by the bootloader].
> And the cookie is used to match the status information with the approporiate
> packet ?
The driver also gets the used ac queue index from the tx feedback message.
So it knows in which tx_status queue it has to look, but that's only
a minor detail.
> Though for ath9k_htc this would mean changes in both the host and FW,
> the host has to queue up packets in some kind of queue and process them
> on reception of status interrupts. The FW has to be changed to actually
> deliver the TX status information. :)
You only have to have a sane tx status if the IEEE80211_TX_CTL_REQ_TX_STATUS
flag is set. In all other cases, the IEEE80211_TX_STAT_ACK handling is
*optional*. In fact if you don't set the TX_STAT_ACK flag, mac80211 will
automatically do the right thing when it sees that a STA has become
"temporarily" unavailable.
> It does make it a bit neat to have such a mechanism. And for AP mode,
> I would think that it's kinda essential unless someone comes with an
> ingenious way of solving the PS race for drivers that don't set
> IEEE80211_HW_REPORTS_TX_ACK_STATUS. :-)
Sure, IEEE80211_HW_REPORTS_TX_ACK_STATUS would be the way to go.
Especially because IEEE80211_HW_PS_NULLFUNC_STACK also benefits
from it.
Best regards,
Chr
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