Ath10k probe response error related to mac80211 commit.

Ben Greear greearb at
Thu Sep 1 13:52:15 PDT 2016

On 09/01/2016 11:53 AM, Johannes Berg wrote:
> On Thu, 2016-09-01 at 11:23 -0700, Ben Greear wrote:
>> Could easily be that others are corrupted too, but since probe resp
>> is bad, the association will not proceed.
> makes sense.
>> Heh, I spent 4 days tracking this down, so I wanted to be precise in
>> my bug report :)
> Ahrg, ouch. Sorry about that. I really didn't think the flag would
> cause any issues for anyone.
>> The result I see is that there is an extra 10 bytes at the end of the
>> frame on air.  But, it looks like the exact same pkt is sent to the
>> firmware both with and without this patch.  Maybe the firmware is
>> using the wrong tid or something like that due to how the station is
>> created differently with this patch.
> That makes no sense though, unless this only happens on say the second
> station that connects? Until the first station sends an authentication
> frame, that patch really should have no impact whatsoever.

Ok, I found the problem.

In the 10.1 firmware (at least), it will force the TID to be NON-QOS-TID
if the peer object does not have the qos_enabled flag set.  This is probably
a work-around for some other thing lost in antiquity.

When using my firmware that puts mgt frames over HTT, the TID for mgt
frames was being over-ridden and set to non-qos TID.  Due to other
hackery and work-arounds, mgt frames cannot be sent on the non-qos
TID because they will be put on-air 10 bytes too long.  They must be
sent on the mgt-tid or non-pause tid.

I am guessing that somehow this mac80211 change creates a peer early
that does not have the qos logic enabled, and so that is why I suddenly
started hitting this bug.

Probably stock firmware is OK since it uses a second tx path for management,
and I guess that by whatever time it starts sending non-mgt frames the
qos-enabled logic is set properly.

I can fix this in my firmware by making it not over-ride the TID in
this case.


Ben Greear <greearb at>
Candela Technologies Inc

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