wcn6855 - stuck in 20Mhz on rx, but full 80mhz on tx

[Yaroslav Isakov]

Hello! I managed to get another router, Asus TUF-AX6000 (with openwrt,
too), and on this one, there is the same problem with rx
bitrate/channel width display, in AC mode.

When I'm switching to AX, there is no display problem (it shows
HE-VCS, even 160 Mhz width), but, the speed of download (measured via
iperf3 -c -R on laptop) is the same as in AC mode, around 150 mbit,
while upload speed is around 800 mbit. I tried 80 Mhz, I tried
different firmware versions, available on
https://github.com/kvalo/ath11k-firmware/tree/master/WCN6855/hw2.0,
but the issue is still the same. I tried to disable power_save,
without any results. It seems that the issue is with WCN6855, not with
router, as my phone managed to reach ~800 mbit download (using iperf3,
too), from the same router. What can I provide, to debug it further?

ср, 27 дек. 2023 г. в 10:32, Yaroslav Isakov <yaroslav.isakov at gmail.com>:
>
> чт, 14 дек. 2023 г. в 21:29, Yaroslav Isakov <yaroslav.isakov at gmail.com>:
> >
> > чт, 14 дек. 2023 г. в 16:11, Kalle Valo <kvalo at kernel.org>:
> > >
> > > Yaroslav Isakov <yaroslav.isakov at gmail.com> writes:
> > >
> > > > Thank you for answer, unfortunately, I would prefer to stay on
> > > > openwrt, until it will be ruled out, that issue is not with my laptop.
> > >
> > > I'm not asking you to switch your firmware, I was merely asking if you
> > > had tested this with a stock firmware or not. The more datapoints we
> > > have the better chances there are to fix this.
> >
> > Unfortunately, I did not test it with stock firmware.
> >
> > >
> > > BTW, please don't top post:
> > >
> > > https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches#do_not_top_post_and_edit_your_quotes
> >
> > Sorry, my bad - this is what Gmail does by default. Thank you for pointing out!
> >
> > >
> > > --
> > > https://patchwork.kernel.org/project/linux-wireless/list/
> > >
> > > https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
>
> Hello!
>
> I debug this issue further, a bit - it seems that it might be a
> display issue. I enabled debug for ath11k driver, and it showed me
> ath11k_pci 0000:02:00.0: mac peer <peer-address> phymode 11ac-vht80
>
> Also, when testing with iperf3, it showed me 300 mbit/s, and it was
> limited by CPU on router (ksoftirqd was 99%), which is much higher
> than 150 mbit showed in iw dev wlan0 link
>
> I also tried to use 802.11n on router (HT40), and with such setting,
> iw dev wlan0 link showed me 300 mbit, with 40 mhz channel width
> (although iperf3 showed 200 mbit) - so, it seems that this issue is
> appearing only on VHT.
>
> My phone (Pixel 7) was able to provide me HE, with which I did not
> have such issue. I cannot downgrade it to VHT, to test, if the issue
> will be reproduced with phone-provided WiFi, too (after disabling
> 802.11ac in wpa_supplicant, it rejected to find the network)
>
> P.S. I updated firmware for laptop wifi, from
> https://github.com/kvalo/ath11k-firmware/tree/master/WCN6855/hw2.0,
> but, it did not change anything.