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From:   Jean-Pierre TOSONI <jp.tosoni@acksys.fr>
To:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: mac80211+ath9k AP fails to honour power save mode from client
Thread-Topic: mac80211+ath9k AP fails to honour power save mode from client
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Date:   Thu, 18 Jul 2019 14:52:05 +0000
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Hello list,

Context:

 I am using one device in AP mode, the other in client mode.
 The client uses wpa_supplicant to do *background scan to other channels th=
at the data channel*.
 I am running iperf (UDP) *from the AP* to the client.

 My device is Cavium development board-based (Octeon III CPU), equipped wit=
h Compex WLE350NX.
 It used to work correctly with kernel 3.18 and an old 2015 wireless backpo=
rt.
 Now I updated to kernel 4.9 and the wireless backport 4.19.32-1, the last =
one from the OpenWRT trunk. (previously I used backport-2017-11-01 with the=
 same failure).

 I am running wireshark with Airpcap to spy the wireless link.

Problem:

 When the client scans offchannel, it correctly sends nullfunc frames aroun=
d the offchannel period, with the PM bit set then unset.

 However, during this time, the AP continues to send data to the client.
  =20
 This results in a lot of lost frames, though I set the powersave buffers t=
o high values on the AP side.


After some research I saw that the same kind of problem was fixed [1] and e=
ven re-fixed, but since there where so many changes in the queue management=
, I cannot really compare his work and the current state of the driver.

Any idea / patch / directions of research ?

J.P. Tosoni - ACKSYS

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/comm=
it/?id=3D5519541d5a5f19893546883547e2f0f2e5934df7=20