[OpenWrt-Devel] mt76 issues on 18.06 HEAD - was: 18.06.2 branching/builds

Felix Fietkau nbd at nbd.name
Thu Feb 7 08:30:51 EST 2019

On 2019-02-04 22:57, Stijn Segers wrote:
> Op zondag 3 februari 2019 om 14:54 schreef Felix Fietkau <nbd at nbd.name>:
>> On 2019-02-02 19:08, Stijn Segers wrote:
>>>  Hi Felix,
>>>  I built 18.06 HEAD with your 2019-01-30 bump, and with the
>>>  mt76-disable-edcca.patch applied. That seemed very stable (up since
>>>  30/01 evening, very high throughput - never seen anything close to 
>>> 50
>>>  MBps on my 2x2 client before; I barely got close to 25 MBps 
>>> before). No
>>>  laggy feeling, so didn't check ping. Wireless wasn't used in the
>>>  morning or the day, but I have tried to stress it in the evening
>>>  (31/01) -transferred about 65 GiB of data over the WLAN (scp). No
>>>  hiccups whatsoever.
>>>  I then reverted to vanilla 18.06 HEAD 31/01, so none of the patches
>>>  applied, and the connection kept working but page loading in the
>>>  browser e.g. would occasionally be slow (nothing else chewing on my
>>>  network connection). I checked ping, and it was all over the place
>>>  again (from sub-milliseconds to 10 ms, occasionally 100ms to other
>>>  devices on the LAN). I suppose there's no real value in those 
>>> numbers,
>>>  but it does quantify the feeling of the wireless 'choking' 
>>> momentarily,
>>>  then picking up again. After like half an hour, wireless would hang 
>>> on
>>>  my laptop: I was unable to ping anything, web pages stopped loading
>>>  altogether. Same thing on my smartphone. However, when I disabled
>>>  wireless on both clients, then turned it on again, the connection
>>>  started working once more; that didn't happen on the previous mt76
>>>  bumps. There the radio would just seem to die like explained in the 
>>> bug
>>>  report.
>> Thanks, that information was very helpful. Did you run those tests on
>> 2.4 GHz or 5 GHz?
> Hi Felix,
> 5 GHz only (I don't use the 2,4 GHz radio).
>>>  Since that hang already happened within the hour, I ran a new build
>>>  with the most recent mt76 bump (2019-01-31) together with the 
>>> 'disable
>>>  edcca' patch. That has been working fine so far (although I'm not
>>>  hitting 50 MBps anymore :-P ). It's been up since Friday afternoon, 
>>> so
>>>  almost 30 hours now. The radio gets shut down at night, but I've 
>>> been
>>>  using it for hours and no issues as far as I can tell.
>>>  Do you want me to try the second patch, or is this OK
>> No need. I've pushed a whole bunch of ED/CCA related patches to 
>> mt76.git
>> (haven't bumped OpenWrt git yet).
>> Could you please test that latest version (commit
>> e301f2349a191c845b6bd2d487e64591ac2ed64d)?
> I just rebuilt your 2019-02-03 bump (copied the Makefile from master to 
> the 18.06 package feed), installed the kmods on top of my existing 
> 18.06 build and rebooted.
> Initially it seemed fine, although the connection seemed a bit laggy at 
> first but that stabilised. My smartphone then just disconnected after 
> an hour (router uptime 1:15' +-) and the AP was not visible anymore 
> despite 'wifi status radio0' saying it was still up. Dmesg was 
> completely silent (nothing related to mt76 or the AP dying).
> 'Wifi reload' brought it back temporarily - it then only took a few 
> minutes to go down again though, for the AP to disappear again and this 
> second time the MCU timeout messages reappeared like in the bug report 
> on Flyspray.
> I didn't have either of your previous patches applied (so 'vanilla' 
> mt76 2019-02-03). I'm rolling back to vanilla 18.06 + your ED/CCA patch 
> for now. If you need any other info/need me to test/check other things, 
> let me know. (I hope this is software and not dying hardware, I 
> wouldn't be able to tell the difference.)
> Thanks for your help already so far.
Thanks for testing!
Does this issue happen for you only on 2.4 GHz, or also on 5 GHz?
My patches seem to have resolved the hang for at least one other user.
I suspect that this is way more likely to happen on 2.4 GHz because of
all the extra noise, so I'm considering disabling ED/CCA for 2.4 GHz.

- Felix

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