Re: ath9k_htc: virtual interfaces, AP connection drop & kernel warning

[wim torfs <wtorfs@gmail.com>]

On 07/22/2015 07:16 PM, Oleksij Rempel wrote:
> Am 22.07.2015 um 18:37 schrieb Rolf Anderegg:
>>
>> On 16/07/15 13:54, Oleksij Rempel wrote:
>>> Am 13.07.2015 um 13:52 schrieb Rolf Anderegg:
>>>>
>>>> I suspect that there are bandwidth/speed issues when dealing with USB
>>>> adapters, but that does not inherently mean that the connection is prone
>>>> to drop, right? Doesn't that mean that I am leaking packages somewhere
>>>> along the way? What else could I be looking for?
>>>
>>> The packages can drop if you will do channel scan. STA mode need some
>>> seconds to complete channel scan. It means AP will be all the time
>>> unavailable.
>>
>> Ok, that may be. Then again why am I not experiencing the same
>> connection drop on my ath5k setup? Because the channel scan is more
>> likely to be completed in due time?
>
> Yes, channel scantime on usb device is match longer then on pci.
>

May I ask for the reason it takes a longer time to complete the scanning 
on a USB device compared to a PCI device? I assume the internals of an 
ath9k PCI device is similar as that of an ath9k_htc USB device, so is it 
purely the bus speed that affects this time? Or is the USB device a 
smaller version of the chipset on the PCI device and therefore with a 
lower speed due to power concerns?

If it is due to the bus speed, would it be possible to decouple the 
scanning process from the bus, that is, I assume that the hardware 
performs all the necessary channel switching and channel sensing, so why 
not allow the hardware to gather such information and transfer the 
results in a single burst to the host over the USB bus? Or is the 
channel switching controlled by the host and it takes a lot of time due 
to the duration of transmitting the channel switching commands to the 
USB device?

Thanks,

Wim.