Bug 55751 - carl9170: monitor mode hangs due to channel changes
Summary: carl9170: monitor mode hangs due to channel changes
Status: NEW
Alias: None
Product: Drivers
Classification: Unclassified
Component: network-wireless (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: drivers_network-wireless@kernel-bugs.osdl.org
Depends on:
Reported: 2013-03-25 23:09 UTC by Marco
Modified: 2022-03-19 19:08 UTC (History)
2 users (show)

See Also:
Kernel Version: 3.6.3
Regression: No
Bisected commit-id:

patch (7.78 KB, patch)
2013-03-25 23:47 UTC, Christian Lamparter
Details | Diff

Description Marco 2013-03-25 23:09:01 UTC
Opening a bug per request.  Discussed 





I'm seeing a problem with the carl driver.  If I change channels
repeatedly on the 2.4ghz band, monitoring (e.g. tcpdump) will
eventually halt.  I've seen this on various versions of the carl
driver/firmware (both from 1.9.4 to 1.9.7)

After monitoring has hung, changing to a 5ghz channel, causes
monitoring to resume.  Bouncing the interface (ip link set mon0
down/up) also fixes it.

Here are some steps to reproduce:

    # setup interface
    iw wlan0 interface add mon0 type monitor
    ip link set mon0 up

    # start channging channels
    while true ; do for i in 1 6 11 ; do iw mon0 set channel $i ; \
    sleep .250 ; done ; done

In a second terminal:
    tcpdump -i mon0

Wait until tcpdump stops printing.  I've seen the failure rate vary
greatly, sometime minutes, sometime hours, but usually less then an


Marco Fonseca
Comment 1 Adrian Chadd 2013-03-25 23:37:07 UTC
Fast channel change is not really supported or stable on the AR9170.

Please disable it for now!
Comment 2 Christian Lamparter 2013-03-25 23:47:28 UTC
Created attachment 96171 [details]

[PATCH] carl9170: remove fast channel change feature
(sent to linux-wireless and Linville)

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