[rt2x00-users] [RFC/RFT 00/15] Beaconing updates and tasklet conversion

Johannes Stezenbach js at sig21.net
Fri Jan 7 07:07:51 EST 2011

On Thu, Jan 06, 2011 at 06:02:23PM +0100, Helmut Schaa wrote:
> Am Donnerstag, 6. Januar 2011 schrieb Johannes Stezenbach:
> > Q1: IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING is set for rt2800pci,
> >     which means mac80211 will not queue the frame but send it
> >     to the driver immediately.  Thus ieee80211_get_buffered_bc()
> >     will not return any frames.  Right?
> It's exactly the other way round. If IEEE80211_HW_HOST_BROADCAST_PS_BUFFERING
> is set mac80211 will buffer mc and bc frames for us and we can retrieve them
> via ieee80211_get_buffered_bc.

Well, duh, seems I can't read the code... embarassing...

> > I guess a possible way out for rt2800usb would be to read
> > the TBTT_TIMER register and then set a hrtimer to fire
> > at the time when PRE_TBTT irq would fire for rt2800pci.
> > Any opinions on this?
> Hmm, interessting approach. You won't get 100% accuracy but sounds
> feasible.

Well, with wireless well never get 100% anyway, but I'm hoping
to get an improvement.  The end goal is reliable mDNS/UPnP.

> An other way I thought of would be to enable PBF_LOOP_EN in MAC_SYS_CTRL. I
> never tried that but it would mean that the rx path will trigger when we tx
> frames. And when we "receive" a beacon we've just sent out we could trigger
> the bc buffer flush. Just an idea ...

Sounds interesting, but has likely too much overhead unless we could
filter to only loopback beacons, not data frames.


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