Re: wlcore update breaks on 4.9 and 4.4 kernel branches

From: Dietmar May <dmay@intellastar.com>
To: Sasha Levin <sashal@kernel.org>
Cc: stable@vger.kernel.org, linux-wireless@vger.kernel.org
Subject: Re: wlcore update breaks on 4.9 and 4.4 kernel branches
Date: Tue, 11 Dec 2018 15:34:40 -0500	[thread overview]
Message-ID: <82d68b26-3c95-af35-86bb-c17855da00ce@intellastar.com> (raw)
In-Reply-To: <20181202150813.GG221015@sasha-vm>

Sasha,

I've verified that 4.9.143 no longer exhibits this problem.

The revert hasn't shown up in 4.4 yet; but I'll verify once merged there.

Thanks,
Dietmar
------------------------------------------------------------------------
On 12/2/18 10:08 AM, Sasha Levin wrote:
> On Thu, Nov 29, 2018 at 05:56:31PM -0500, Dietmar May wrote:
>> I've run into some problems which appear due to (a) recent patch(es) 
>> on the wlcore wifi driver.
>>
>> 4.4.160 - commit 3fdd34643ffc378b5924941fad40352c04610294
>> 4.9.131 - commit afeeecc764436f31d4447575bb9007732333818c
>>
>> 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.
>
> Given that this patch went in through AUTOSEL, I've queued up a revert
> of it (sorry for the trouble!).
>
> I'll link this mail in the revert message. If anyone feels that this
> patch should be in any of the LTS trees then either reply to this thread
> or start a new one on stable@vger.kernel.org.
>
> -- 
> Thanks,
> Sasha

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