ath: phy1: DMA failed to stop in 10 ms

From: Andrej Gelenberg
Date: Fri Nov 28 2014 - 20:27:34 EST

Hallo,

i got some problems with my Qualcomm Atheros AR9485 wlan pcie card. I
use my card as access point (with hotspotd) on amd64 machine. I use
self compiled vanilla kernel 3.17.4 and a get a lot of
"DMA failed to stop" messages in my kernel log. I found some reports on
similar errors for *wrt, ubuntu and other distros in various
operation modes (ap and client). Increasing the timeout in mac.c to 100
ms do not help. iommu=soft do not help either and GART iommu is not an
option (usb don't work for me with amd_iommu=off). I found this patch:
https://dev.openwrt.org/browser/trunk/package/mac80211/patches/552-ath9k_rx_dma_stop_check.patch?rev=34910 ,
which seems to apply to my problem, but i am not sure if it is a proper
solution.

Regards,
Andrej Gelenberg

PS: here some kernel logs:

Nov 29 01:12:08 [kernel] [ 956.514069] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0002ad00
Nov 29 01:12:08 [kernel] [ 956.514089] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
Nov 29 01:12:08 [kernel] [ 956.514091] ------------[ cut here ]------------
Nov 29 01:12:08 [kernel] [ 956.514096] WARNING: CPU: 2 PID: 242 at drivers/net/wireless/ath/ath9k/recv.c:498 ath_stoprecv+0x137/0x150 [ath9k]()
Nov 29 01:12:08 [kernel] [ 956.514097] Modules linked in: bluetooth ath9k ath9k_common ath9k_hw ath loop fglrx(PO) led_class firewire_ohci firewire_core cdc_acm serio_raw 3c59x wmi [last unloaded: ath]
Nov 29 01:12:08 [kernel] [ 956.514106] CPU: 2 PID: 242 Comm: kworker/u16:8 Tainted: P W O 3.17.4+ #97
Nov 29 01:12:08 [kernel] [ 956.514107] Hardware name: To be filled by O.E.M. To be filled by O.E.M./SABERTOOTH 990FX, BIOS 1604 10/16/2012
Nov 29 01:12:08 [kernel] [ 956.514110] Workqueue: phy1 ath_reset_work [ath9k]
Nov 29 01:12:08 [kernel] [ 956.514112] 0000000000000009 ffff880810713d00 ffffffff81ba31e8 0000000000000000
Nov 29 01:12:08 [kernel] [ 956.514113] ffff880810713d38 ffffffff8111be9c ffff8808075499e0 ffff88080a60a018
Nov 29 01:12:08 [kernel] [ 956.514115] 0000000000000000 ffff88080a60a360 ffff8808075499e0 ffff880810713d48
Nov 29 01:12:08 [kernel] [ 956.514117] Call Trace:
Nov 29 01:12:08 [kernel] [ 956.514122] [<ffffffff81ba31e8>] dump_stack+0x4d/0x6f
Nov 29 01:12:08 [kernel] [ 956.514125] [<ffffffff8111be9c>] warn_slowpath_common+0x8c/0xc0
Nov 29 01:12:08 [kernel] [ 956.514127] [<ffffffff8111bf8a>] warn_slowpath_null+0x1a/0x20
Nov 29 01:12:08 [kernel] [ 956.514130] [<ffffffffc0164237>] ath_stoprecv+0x137/0x150 [ath9k]
Nov 29 01:12:08 [kernel] [ 956.514132] [<ffffffffc015dfea>] ath_prepare_reset+0x4a/0x70 [ath9k]
Nov 29 01:12:08 [kernel] [ 956.514135] [<ffffffffc016170b>] ath_reset_internal+0x9b/0x1d0 [ath9k]
Nov 29 01:12:08 [kernel] [ 956.514138] [<ffffffffc0161860>] ath_reset+0x20/0x40 [ath9k]
Nov 29 01:12:08 [kernel] [ 956.514140] [<ffffffff81132ac0>] ? pwq_dec_nr_in_flight+0x50/0xb0
Nov 29 01:12:08 [kernel] [ 956.514143] [<ffffffffc0161895>] ath_reset_work+0x15/0x20 [ath9k]
Nov 29 01:12:08 [kernel] [ 956.514145] [<ffffffff81132c65>] process_one_work+0x145/0x3f0
Nov 29 01:12:08 [kernel] [ 956.514147] [<ffffffff8113358b>] worker_thread+0x6b/0x490
Nov 29 01:12:08 [kernel] [ 956.514149] [<ffffffff81133520>] ? init_pwq.part.32+0x10/0x10
Nov 29 01:12:08 [kernel] [ 956.514151] [<ffffffff81137c9b>] kthread+0xdb/0x100
Nov 29 01:12:08 [kernel] [ 956.514153] [<ffffffff81137bc0>] ? kthread_create_on_node+0x1a0/0x1a0
Nov 29 01:12:08 [kernel] [ 956.514155] [<ffffffff81bac1ac>] ret_from_fork+0x7c/0xb0
Nov 29 01:12:08 [kernel] [ 956.514157] [<ffffffff81137bc0>] ? kthread_create_on_node+0x1a0/0x1a0
Nov 29 01:12:08 [kernel] [ 956.514159] ---[ end trace e94ce9b429eb9bb7 ]---
Nov 29 01:12:14 [kernel] [ 961.748265] ath: phy1: Failed to stop TX DMA, queues=0x00c!
Nov 29 01:12:14 [kernel] [ 961.759785] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
Nov 29 01:12:14 [kernel] [ 961.759809] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
Nov 29 01:12:23 [kernel] [ 971.465967] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0002ad00
Nov 29 01:12:23 [kernel] [ 971.465993] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
Nov 29 01:12:54 [kernel] [ 1002.393560] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000ad00
Nov 29 01:12:54 [kernel] [ 1002.393580] ath: phy1: Could not stop RX,
we could be confusing the DMA engine when we start RX up

...

[ 1953.389445] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0002a800
[ 1953.389477] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
[ 1963.618985] ath: phy1: Failed to stop TX DMA, queues=0x004!
[ 1963.630517] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[ 1963.630546] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
[ 1992.904614] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000ad00
[ 1992.904643] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
[ 2071.259582] ath: phy1: Failed to stop TX DMA, queues=0x104!
[ 2071.271109] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[ 2071.271134] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
[ 2076.884579] ath: phy1: Failed to stop TX DMA, queues=0x004!
[ 2076.896107] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[ 2076.896131] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
[ 2082.517123] ath: phy1: Failed to stop TX DMA, queues=0x004!
[ 2082.528633] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0000a400
[ 2082.528661] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
[ 2097.981066] ath: phy1: Failed to stop TX DMA, queues=0x004!
[ 2097.992571] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0002a800
[ 2097.992596] ath: phy1: Could not stop RX, we could be confusing the DMA engine when we start RX up
[ 2133.206513] ath: phy1: DMA failed to stop in 10 ms AR_CR=0x00000024 AR_DIAG_SW=0x02000020 DMADBG_7=0x0002ad00
[ 2133.206541] ath: phy1: Could not stop RX, we could be confusing the
DMA engine when we start RX up
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