Arch Linux

Description:

Recently, i noticed frequent wifi crashes while downloading a large file on my Qualcomm Atheros AR9485 card. Reloading the ath9k module temporarily resolves the problem, but it will crash again after downloading about 100MB.

While downloading, dmesg keeps repeating message like this:

[ 138.946120] ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[ 163.649854] ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000028 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[ 164.864785] wlp6s0: authenticate with xx:xx:xx:xx:xx:xx
[ 164.885462] wlp6s0: send auth to xx:xx:xx:xx:xx:xx (try 1/3)
[ 164.905512] wlp6s0: authenticated
[ 164.906987] wlp6s0: associate with xx:xx:xx:xx:xx:xx (try 1/3)
[ 164.919448] wlp6s0: RX AssocResp from xx:xx:xx:xx:xx:xx (capab=0x431 status=0 aid=1)
[ 164.919614] wlp6s0: associated
[ 164.919793] ath: EEPROM regdomain: 0x8038
[ 164.919794] ath: EEPROM indicates we should expect a country code
[ 164.919796] ath: doing EEPROM country->regdmn map search
[ 164.919798] ath: country maps to regdmn code: 0x37
[ 164.919801] ath: Country alpha2 being used: BE
[ 164.919803] ath: Regpair used: 0x37
[ 164.919806] ath: regdomain 0x8038 dynamically updated by country element


After the second "DMA failed to stop" message, the systemd journal shows an AP disconnect (reason=4) message.

I succeeded to narrow it down to version 4.20.0-arch1-1 (which changes a number of kernel config options). In 4.19.12.arch1-1, the dmesg message appears and the connection drops, but is restored quickly afterwards (fast enough for the connection to be usable). In 4.20.0-arch1-1, the reconnect does not happen and a manual reload of the module is required.

As to the DMA errors, they become less frequent with ANI disabled (as suggested in some forums), but they do not go away.

Feel free to ask for more debugging info.


Additional info:
* package version: 4.20.0-arch1-1
* kernel module: ath9k
* pci device: Qualcomm Atheros AR9485 Wireless Network Adapter (168c:0032)


Steps to reproduce:
1. Boot with linux 4.20.0-arch1-1
2. Start a large download
3. After about 100MB, download stalls and wifi disconnects
Using the previous version of the package, download of +1GB work fine.