[ath9k-devel] [RFC 3/3] ath9k: add spectral scan feature

[Felix Fietkau <nbd@openwrt.org>]

On 2012-12-05 11:40 AM, Simon Wunderlich wrote:
>> I suggest experimenting around with those particular parameters. You
>> should be able to coax out specific numbers of spectral scan events
>> when you set the COUNT parameter to something other than 8. But
>> polling that bit isn't needed. It should be asynchronous.
> 
> As I said, on AR9220 it appears I get 8 samples when doing setting 
> AR_PHY_SPECTRAL_SCAN_COUNT to 8 (plus maybe some other "stuff"/non-samples).
> On AR9380 I'm not so sure. Probably need to play with it a little
> more. Also, I don't know what "SHORT REPEAT" is supposed to mean, etc.
> 
> About polling, you mean the SCAN_ACTIVE bit? It is probably only
> needed when I want to trigger for few samples and want to be informed when
> it's finished -  which is a good thing when doing spectral scan (change channel,
> start and wait for samples, change again). But we probably don't need to wait
> for the "background spectral scanning" mode, that's right. If someone wants
> to implement detection for interfering radio users, that mode would be useful.
> I don't need it, but can prepare the neccesary functions.
> 
> So I'd repost then:
>  * ath9k/debugfs only patch for now, as Johannes suggested - I think we
>    should concentrate on this for now (their are still a lot of open
>    questions in my initial mail regarding sample interpretation etc)
>  * split commands into enable/disable/configure/trigger
>  * maybe add some defines for magic values (if I find any)
> 
> I'd like this patchset to make the graphical spectral scan possible (as
> a Ubiquiti Airview), and give others the opportunity to add own features
> (pattern matching etc) on top of it. However I (currently) don't plan to
> do the latter myself.
How about using relay (Documentation/filesystems/relay.txt) to stream
sample data to user space via the debugfs file?
That way you don't have to keep a linked list of small struct fft_sample
buffers in the kernel and you can stream much more data efficiently with
little kernel side overhead.
It also makes pushing the streaming data to a network socket via
sendfile much more efficient.

- Felix