Re: [PATCH v3 1/1] mac80211: tell driver when dtim change detected

[Johannes Berg <johannes@sipsolutions.net>]

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On Mon, 2010-01-25 at 10:35 -0800, Jouni Malinen wrote:
> On Fri, Jan 22, 2010 at 08:03:01PM +0100, Johannes Berg wrote:
> > The other solution I see is that we add a new step before or after the
> > direct probe step, which would just be "wait for a beacon". This would
> > ensure we have both probe and beacon information always ready. It would
> > also ensure we have both probe and beacon info for our new userspace
> > reporting of that.
> 
> I'm somewhat concerned about this as an unconditional change for our
> association process due to the extra latency it adds. At minimum, I
> would like to see a driver flag that can be used to indicate that such
> behavior is really required and skip the extra wait if the driver does
> not need the Beacon frame before association.
> 
> For most cases, I would also assume it should be possible to update the
> PS settings after having received the first Beacon frame after
> association, but if that is not enough, allowing the driver to request
> mac80211 to wait with association sounds reasonable. I just don't want
> to see additional 50 msec or so (or much worse if the AP is configured
> with insanely long beacon interval) delay popping up with every
> association by default..

Yeah that's a good point, I wondered about that too. I'll look into this
in more detail and see if we can tell the driver about the DTIM period
only with CONF_PS and enable that only after a beacon.

johannes

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