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mrBen

Member

From: France

Registered: 2019-07-15

Posts: 1

Website

Random wifi disconnects AR9485 (phy0: DMA failed to stop in 10 ms)

Since a few months my wifi connection randomly stop working and the only fix I've found is to reboot my machine. The problem usually appear after few hours of usage, but sometime I get disconnect as soon as a minute after booting. I don't think it's an hardware problem as the wireless work perfectly fine on windows.

I'm pretty sure that problem started before the 5.0 kernel (probably 4.20) and it is definitely still here today (linux 5.2.arch2-1).

Here is the relevant output from lspci -v:

Network controller: Qualcomm Atheros AR9485 Wireless Network Adapter (rev 01)
Subsystem: AzureWave AR9485 Wireless Network Adapter
Flags: bus master, fast devsel, latency 0, IRQ 18
Memory at f7a00000 (64-bit, non-prefetchable) [size=512K]
Expansion ROM at f7a80000 [disabled] [size=64K]
Capabilities: [40] Power Management version 2
Capabilities: [50] MSI: Enable- Count=1/4 Maskable+ 64bit+
Capabilities: [70] Express Endpoint, MSI 00
Capabilities: [100] Advanced Error Reporting
Capabilities: [140] Virtual Channel
Capabilities: [160] Device Serial Number 00-00-00-00-00-00-00-00
Kernel driver in use: ath9k
Kernel modules: ath9k

Here is what dmesg give me soon after a disconnect:

[ 2364.308768] ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000028 AR_DIAG_SW=0x02000020 DMADBG_7=0x0002a800
[ 2929.113548] ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[ 2953.463580] ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000028 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[ 2954.648979] wlp3s0: authenticate with 68:a3:78:00:cd:1f
[ 2954.670316] wlp3s0: send auth to 68:a3:78:00:cd:1f (try 1/3)
[ 2954.676072] wlp3s0: authenticated
[ 2954.678102] wlp3s0: associate with 68:a3:78:00:cd:1f (try 1/3)
[ 2954.683030] wlp3s0: RX AssocResp from 68:a3:78:00:cd:1f (capab=0x411 status=0 aid=2)
[ 2954.683123] wlp3s0: associated

Note that even if the messages seems to indicate that the problem is fixed, my computer still act as if there was no connection.

I've done a bit of research but I can't find a suitable fix. Many post are just unanswered, or the problem was fix by changing the network card or by a kernel update from 3.x to another 3.x...

syssunn

Member

Registered: 2019-02-10

Posts: 6

Re: Random wifi disconnects AR9485 (phy0: DMA failed to stop in 10 ms)

Same issue. Same wireless adapter. But I only noticed after the update.

Network controller: Qualcomm Atheros AR9485 Wireless Network Adapter (rev 01)
Subsystem: Qualcomm Atheros AR9485 Wireless Network Adapter
Flags: bus master, fast devsel, latency 0, IRQ 16
Memory at f7c00000 (64-bit, non-prefetchable) [size=512K]
Expansion ROM at f7c80000 [disabled] [size=64K]
Capabilities: <access denied>
Kernel driver in use: ath9k
Kernel modules: ath9k

[40415.545115] ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[51475.728069] wlp1s0: authenticate with 56:e7:ee:7b:55:bc
[51475.756404] wlp1s0: send auth to 56:e7:ee:7b:55:bc (try 1/3)
[51476.144532] wlp1s0: send auth to 56:e7:ee:7b:55:bc (try 2/3)
[51476.234460] wlp1s0: send auth to 56:e7:ee:7b:55:bc (try 3/3)
[51476.354161] wlp1s0: authentication with 56:e7:ee:7b:55:bc timed out
...
...
...
[51491.514017] wlp1s0: authenticate with 56:e7:ee:7b:55:bc
[51491.544315] wlp1s0: send auth to 56:e7:ee:7b:55:bc (try 1/3)
[51491.546773] wlp1s0: authenticated
[51491.553422] wlp1s0: associate with 56:e7:ee:7b:55:bc (try 1/3)
[51491.558995] wlp1s0: RX AssocResp from 56:e7:ee:7b:55:bc (capab=0x431 status=0 aid=1)
[51491.559105] wlp1s0: associated
[51491.567136] IPv6: ADDRCONF(NETDEV_CHANGE): wlp1s0: link becomes ready

Edit: *only noticed after...

Last edited by syssunn (2019-07-23 03:03:28)

snazza

Member

Registered: 2011-01-24

Posts: 11

Re: Random wifi disconnects AR9485 (phy0: DMA failed to stop in 10 ms)

I'm adding a reply here  because I've possibly found a solution in this thread by adding

intel_iommu=off

to kernel parameters.
This parameter seems to be only needed set to "on" when using advanced Virtual Machine features like PCI pass-through, so disable it shouldn't be a problem in most cases.

Last edited by snazza (2020-05-29 10:15:59)

syssunn

Member

Registered: 2019-02-10

Posts: 6

Re: Random wifi disconnects AR9485 (phy0: DMA failed to stop in 10 ms)

I'm adding a reply here  because I've possibly found a solution in this thread by adding

intel_iommu=off

to kernel parameters.
This parameter seems to be only needed set to "on" when using advanced Virtual Machine features like PCI pass-through, so disable it shouldn't be a problem in most cases.

I've been testing it for some days, and it's seems the disconnects and DMA errors messages have gone. I added this solution to the Arch Wiki https://wiki.archlinux.org/index.php/Ne … s#Cause_#5.

Last edited by syssunn (2020-08-26 16:59:38)