#21651: Ath9k wifi broken (at least on some devices) in chaos calmer, please add
warnings on release notes
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Reporter: anonymous | Owner: developers
Type: defect | Status: reopened
Priority: high | Milestone:
Component: kernel | Version: Trunk
Resolution: | Keywords:
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Changes (by sergio.callegari@…):
* status: closed => reopened
* resolution: wontfix =>
Comment:
After some search, I found out that disabling Adaptive Noise Immunity
(ANI) fixes the issue for me. The logic used to automatically update the
ANI filter coefficients seems to be very badly broken for my chipset.
Furthermore googling shows that this is a recurrent problem for ATH9K.
Indeed, there are a lot of instructions about disabling ANI via the
/sys/kernel/debug/ieee80211/phy0/ath9k/disable_ani file. However, the
kernels in recent openwrt do not provide such file. Conversely, ANI can be
disabled by echoing a 0 into /sys/kernel/debug/ieee80211/phy0/ath9k/ani.
Hence, I would like to advocate again that the release notes of devices
using ath9k are updated to say that ANI is a frequent issue on this
chipset. IMHO, the notes should point out that both very large ping times
(e.g. > 1s) and ping jitter (e.g. ping times in sequences like 0.9 0.9 60
0.8 1.1 90 1.0 1.1 40 ...) can be a likely sign of broken ANI.
Furthermore, they should provide current instructions on how to disable
ANI, both on a test basis that does not survive reboot (e.g. echo 0 >
/sys/kernel/debug/ieee80211/phy0/ath9k/ani) and on a permanent basis that
does.
IMHO this is not a matter of saying that "there might be issues" in a
general way, but to provide an important, punctual bit of knowledge that
exists on this chipset and its (still not so good) linux drivers.
Given the amount of reports that you can find around about the orrible
performance that you can get out of ath9k, I would also suggest to
consider the option to ship with ANI disabled by default, with
instructions on how to test it and permanently activate it as needed.
--
Ticket URL: <https://dev.openwrt.org/ticket/21651#comment:3>
OpenWrt <http://openwrt.org>
Opensource Wireless Router Technology
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