[ath9k-devel] atheros chipset does not recover after going into unresponsive state

[Saurabh Chakrabarti <saurabh.chakrabarti@amideeptech.com>]

Forgot to mention, I'm using kernel 3.14 
(https://github.com/raspberrypi/linux/tree/rpi-3.14.y) and got the 
firmware from here - https://github.com/qca/open-ath9k-htc-firmware.git 
(master branch)

On Tue 20 May 2014 08:01:43 PM IST, Saurabh Chakrabarti wrote:
> I am using TP-link WN721n usb wifi adapter with atheros 9271 chipset
> on raspberry pi. There are times when the wifi interface goes into an
> unresponsive state in which it does not send or receive any packets.
>
> Here's the error log I get as soon as this occurs,
>
> May 16 15:55:13 raspberry kernel: [  240.974619] ath: phy0: Timeout
> waiting for WMI command: WMI_REG_WRITE_CMDID
> May 16 15:55:13 raspberry kernel: [  241.053067] ath: phy0: REGISTER
> WRITE FAILED:(0x4048, -110)
> May 16 15:55:14 raspberry kernel: [  241.737670] ath: phy0: Dropping a
> packet due to TX timeout
>
> When this state is hit, I reboot the system, but after reboot the wifi
> interface(wlan0) does not come back up. Here's the error I get on
> startup in the kernel log,
>
> usb 1-1.2: device descriptor read/64, error -110
>
> Interestingly, it works like a charm when I turn off the power and
> turn it back on(or if I pull the wifi adapter out and insert it back).
> But obviously I cannot do this all the time as the system is at a
> remote location.
>
> Although I would want to know why the interface goes into this state,
> is there anything I can do so that I can atleast reset the interface
> once it goes into this state?
>
> Regards,
> Saurabh Chakrabarti
>