Question on beacon-miss offloading.

Krishna Chaitanya chaitanya.mgit at
Fri Jun 12 07:10:23 PDT 2015

On Fri, Jun 12, 2015 at 6:59 PM, Ben Greear <greearb at> wrote:
> On 06/11/2015 11:03 PM, Michal Kazior wrote:
>> On 12 June 2015 at 01:38, Ben Greear <greearb at> wrote:
>>> On 06/11/2015 02:07 PM, Ben Greear wrote:
>>>> In my ath10k CT firmware, I am disabling the beacon-miss offloading
>>>> to save space and because it will not work with lots of virtual
>>>> stations.
>>>> But, it must be that I need some way to tell the stack that this
>>>> feature is not enabled, because when suddenly kill my AP, then
>>>> the ath10k station connected to it shows endless 'beacon loss' events
>>>> in 'iw events' output, but it never actually loses connection.
>>>> Stock firmware works fine, so probably I just need to disable
>>>> some feature flag when registering the ath10k hardware
>>>> when using CT firmware.
>>>> With stock firmware, I see a quick dissassociation due to inactivity.
>>>> I am having poor luck finding how a driver tells the stack
>>>> it has beacon miss offload or not, so, does anyone know how
>>>> this is controlled?
>>> I still am not sure why stock firmware works, but it appears
>>> the reason mine is failing is that the ACK status for mgt frames
>>> is always set to TRUE since the ath10k wmi-mgt-tx API is so
>>> lame.  So, mac80211 does a probe, ath10k lies and says it was
>>> acked, and mac80211 then things all is well for another few
>>> seconds.
>> mac80211 shouldn't do a Probe Req to an AP on beacon loss because
>> ath10k advertises it supports tx-status report. Hence mac80211 should
>> use NullFunc frames which shouldn't go through wmi-mgmt-tx but htt
>> tx-frm.
>> But then again: NullFunc status reporting via htt tx-frm was broken on
>> 10.1 if memory serves right. I believe it was fixed in 10.2 or 10.2.4.
>> This problem has been effectively obscured on stock 10.1 by the
>> offloaded beacon miss.
> For what it's worth, I looked at the 4.0.4 ath10k yesterday, and it appears
> it
> ignores the message that the 10.1 firmware sends when beacon loss happens
> anyway.  Maybe I misread the firmware's a pile of indirection.
> Do you know how the firmware is supposed to signal beacon loss to
> the host (from the host's perspective).

Normally driver would advertise IEEE80211_HW_CONNECTION_MONITOR
to disable mac80211 from tracking connection. and driver should call
ieee80211_beacon_loss up on receiving beacon loss event from FW
which triggers disconnection in mac80211.

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