Re: Question on beacon-miss offloading.

From: Ben Greear <greearb@candelatech.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	ath10k <ath10k@lists.infradead.org>
Subject: Re: Question on beacon-miss offloading.
Date: Fri, 12 Jun 2015 06:29:15 -0700	[thread overview]
Message-ID: <557ADEAB.80504@candelatech.com> (raw)
In-Reply-To: <CA+BoTQkLyaP-2sHiu7Wn-ZzGj2JnZs4qzQKGu7PiTtUy4d9xLQ@mail.gmail.com>

On 06/11/2015 11:03 PM, Michal Kazior wrote:
> On 12 June 2015 at 01:38, Ben Greear <greearb@candelatech.com> 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 code..it'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).

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

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