BugLink: https://bugs.launchpad.net/bugs/1811077

This reverts commit 3fdd3464 which was
upstream commit 4ec7cece.

From Dietmar May's report on the stable mailing list
(https://www.spinics.net/lists/stable/msg272201.html):

> I've run into some problems which appear due to (a) recent patch(es) on
> the wlcore wifi driver.
>
> 4.4.160 - commit 3fdd3464
> 4.9.131 - commit afeeecc7
>
> Earlier versions (4.9.130 and 4.4.159 - tested back to 4.4.49) do not
> exhibit this problem. It is still present in 4.9.141.
>
> master as of 4.20.0-rc4 does not exhibit this problem.
>
> Basically, during client association when in AP mode (running hostapd),
> handshake may or may not complete following a noticeable delay. If
> successful, then the driver fails consistently in warn_slowpath_null
> during disassociation. If unsuccessful, the wifi client attempts multiple
> times, sometimes failing repeatedly. I've had clients unable to connect
> for 3-5 minutes during testing, with the syslog filled with dozens of
> backtraces. syslog details are below.
>
> I'm working on an embedded device with a TI 3352 ARM processor and a
> murata wl1271 module in sdio mode. We're running a fully patched ubuntu
> 18.04 ARM build, with a kernel built from kernel.org's stable/linux repo <https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.9.y&id=afeeecc764436f31d4447575bb9007732333818c>.
> Relevant parts of the kernel config are included below.
>
> The commit message states:
>
> > /I've only seen this few times with the runtime PM patches enabled so
> > this one is probably not needed before that. This seems to work
> > currently based on the current PM implementation timer. Let's apply
> > this separately though in case others are hitting this issue./
> We're not doing anything explicit with power management. The device is an
> IoT edge gateway with battery backup, normally running on wall power. The
> battery is currently used solely to shut down the system cleanly to avoid
> filesystem corruption.
>
> The device tree is configured to keep power in suspend; but the device
> should never suspend, so in our case, there is no need to call
> wl1271_ps_elp_wakeup() or wl1271_ps_elp_sleep(), as occurs in the patch.
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>