Wcn36xx AP Dropout


Having trouble with AP mode on dargonboard410c running Linux 4.9.

AP mode will work for a while but then after a few hours the SSID is still observable (broadcasting) but the AP point will not accept any connections. The only way to connect to the AP is resetting the dragonboard.

I have be unable to track down where this issue is coming from. Using HostAPD for managing AP mode, and setting it to be high verbosity, I cannot find any problems in the logs.

Any other ideas where this problem might be coming from?




there have been a very large number of bug fixes in the last few months in the wcn36xx driver (the wlan driver used on db410c). Most (if not all) have now been merged into mainline, and we have backported them into our 4.14 release branch, however we are not supporting this branch anymore.

If you cannot upgrade to 4.14, then you might be able to cherry-pick all the bug fixes hopefully without too much pain. Looking at ath-next branch, i can see the following patches to backport. Not all of them are strictly needed, but I would recommend to take them all:

5151a673da43 (ath-next/ath-next) wcn36xx: allocate skbs with GFP_KERNEL during init
6062546d9b7f wcn36xx: Remove useless skb spinlock
1391cce7daf6 wcn36xx: Add missing fall through comment in smd.c
2edfcf2b303c wcn36xx: don't delete invalid bss indices
271f1e65ff38 wcn36xx: don't keep reference to skb if transmission failed
7cae35199bee wcn36xx: check for DMA mapping errors in wcn36xx_dxe_tx_frame()
f276ba06e8b2 wcn36xx: dequeue all pending indicator messages
e5f9908155c9 wcn36xx: Fix firmware crash due to corrupted buffer address
ee35eecb0822 wcn36xx: turn off probe response offloading
2ef00c53049b wireless: Use octal not symbolic permissions
6767b302e1c9 wcn36xx: Check DXE IRQ reason
e5d04670904f wcn36xx: calculate DXE default channel values
6ced7958168f wcn36xx: calculate DXE control registers values
6b8a127bf66d wcn36xx: reduce verbosity of drivers messages
9bfd05e35ac3 wcn36xx: Fix warning due to duplicate scan_completed notification
d0bb950b9f5f wcn36xx: release DMA memory in case of error
4c8cf8df2f42 wcn36xx: fix incorrect assignment to msg_body.min_ch_time
0856655a2547 wcn36xx: Fix dynamic power saving
6d1f37323f5b wcn36xx: Reduce spinlock in indication handler
2f3bef4b247e wcn36xx: Add hardware scan offload support


I think this is same issue has the one in this topic: Access Point wifi connection that hangs up, we have to open an issue.

On my side problem happens on rekeying. Could you try to disable rekeying in your conf file (wpa_group_rekey=0) and let me know.

Bug: https://bugs.96boards.org/show_bug.cgi?id=727


Having trouble with AP mode on dargonboard410c running Linux 4.9.

Anything running that kernel must be at least six months old (maybe
more) and there has been some significant improvements to the DB410C
WiFi over that time. Do you still see problems in the latest 18.01
release (or, given that 18.04 is due “real soon now”, if 18.01 doesn’t
work perhaps with the most recent snapshot).



Sorry. I ended up merely I repeated, with less detail, what others already said (didn’t spot the later contributions when processing my mail this morning… sorry for noise).


I should mention, running the oe-rpb image lovingly built with bitbake.

Was running a pretty old build of 4.9:

in: meta-qcom/recipes-kernel/linux/linux-linaro-qcomlt_4.9.bb

SRCREV ?= "8165c999c87f1fe205e6fad779ded1f3e9bc382f"

Did a build with:

SRCREV = "3e797f5b154e7b382aa1801b022d0d431ca00b86"

And still same problem.

@ndec, i’ll try cherry-picking these patches and get back to you.

@Loic, i’ll look into this keyring issue as well.

Thanks everyone! Fingers crossed!