#19316: ath10k_pci 0000:01:00.0: failed to process fft report: -22
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Reporter: kevindb | Owner: developers
Type: defect | Status: new
Priority: normal | Milestone:
Component: kernel | Version: Trunk
Resolution: | Keywords: ath10k fft
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Comment (by michal.kazior@…):
Replying to [comment:4 el_goretto]:
> Replying to [comment:3 michal.kazior@…]:
> > Replying to [comment:1 anonymous]:
> > > Same issue here on an Archer C5 v1.20 (build r44918 with DFS enabled
like explained here:
http://wiki.openwrt.org/doc/uci/wireless#dfsradar_detection) when setting
channel to "auto" or to a channel requiring DFS.
> > > After a while, it seems the wlan interface can't execute a scan
operation (error with {{{iw phy0 scan}}}).
> > > After a while too (couldn't see if these 2 facts are related), the
channel is changed to "36" forcefully with:
> > > {{{
> > > daemon.info hostapd: wlan0: IEEE 802.11 driver had channel switch:
freq=5180, ht=1, offset=1, width=3, cf1=5210, cf2=0
> > > }}}
> > >
> > > When using a channel not requiring DFS, the log in the ticket is not
visible.
> >
> > DFS channels require APs to listen for radar pulses. If it does detect
one it is required to stop RF radiation and run away to a different
channel. It does this by quickly announcing that to connected stations and
then switching. This is regulated by ETSI and FCC regulatory bodies in
Europe and US respectively.
> >
> > There's also a requirement for AP to assess if a channel is usable
prior to initiating RF radiation on it.
>
> Yes, that's why the AP is not immediatly picking a channel in "auto"
mode, I understand that. But the channel switch does not happen to be
going through the usual "auto" channel pick as it always picks 36. Wiki
says userland tool should be notified and going against a whole channel
selection process. That's clearly not the case.
This is technically not possible because ACS takes time while DFS and CSA
must be respected immediately.
The fact that it always chooses 36 means you don't have channel 149 (and
following) available. DFS/CSA picks a random channel definition from list
of available non-DFS channels. This is per design and is not inherent to
ath10k but to hostapd.
--
Ticket URL: <https://dev.openwrt.org/ticket/19316#comment:6>
OpenWrt <http://openwrt.org>
Opensource Wireless Router Technology
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