Stability connection problems in ath9k kernel 4.7

[Valerio Passini <valerio.passini@unicam.it>]

Hello,

I have found some connection problems since 4.7 release using ath9k that turn 
the wifi pretty useless, I think it might be something in the power management 
because the signal seems really low. Previously, up to kernel 4.6.7 everything 
worked very well.
This is a sample of dmesg in kernel 4.7.2:
 239.898935] wlp4s0: authenticate with XX:XX:XX:XX:XX:XX 
[  239.919995] wlp4s0: send auth to XX:XX:XX:XX:XX:XX  (try 1/3) 
[  239.931877] wlp4s0: authenticated 
[  239.932357] wlp4s0: associate with XX:XX:XX:XX:XX:XX  (try 1/3) 
[  239.942171] wlp4s0: RX AssocResp from XX:XX:XX:XX:XX:XX  (capab=0x431 
status=0 aid=2) 
[  239.942301] wlp4s0: associated 
[  244.802853] ath: phy0: DMA failed to stop in 10 ms AR_CR=0x00000024 
AR_DIAG_SW=0x02000020 DMADBG_7=0x0000
6100                                                                                                         
[  245.931832] wlp4s0: authenticate with XX:XX:XX:XX:XX:XX  
[  245.953028] wlp4s0: send auth to XX:XX:XX:XX:XX:XX  (try 1/3) 
[  245.958702] wlp4s0: authenticated 
[  245.960386] wlp4s0: associate withXX:XX:XX:XX:XX:XX  (try 1/3) 
[  245.980543] wlp4s0: RX AssocResp from XX:XX:XX:XX:XX:XX  (capab=0x431 
status=0 aid=2)

lspci on 4.6.7 kernel:
04:00.0 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 f7900000 (64-bit, non-prefetchable) [size=512K]
        Expansion ROM at f7980000 [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

Probably you need some debugging output, but before recompiling the kernel I 
would like to know if you are interested in any kind of help from me and what 
steps I should take (I'm able to help in testing patches but I'm not familiar 
with git). Thank you

Valerio