Re: [PATCH v3 1/3] cfg80211/nl80211: add support for scheduled scans

[Luciano Coelho <coelho@ti.com>]

On Fri, 2011-05-13 at 12:52 +0200, Johannes Berg wrote:
> On Fri, 2011-05-13 at 12:45 +0200, Stanislaw Gruszka wrote:
> 
> > > because the scheduled scan is a long-term operation and the normal scan
> > > is done for a very short time (and the rest of the stack assumes it will
> > > complete quickly enough as not to interfere with the connection.
> > 
> > Hmm, is this drawback of implementation or can not be done technically
> > (question to myself :-) ? I can image that in ideal case hardware scanning
> > will not affect normal operation, no matter how long it will take.
> > Software scan is much worse, since we have to change channels manually.
> > We currently share code between software scan and hardware scan in
> > mac80211. Perhaps separating hw and sw scan code, would be a good idea
> > and allow to consolidate hw scan and sched scan. I planning to look
> > at this more closely.
> 
> Well, it's also a semantic question. If you trigger a scan, you expect a
> result (or an abort) after a while. It could of course be extended with
> a new attribute, but the error checking for that gets complicated,
> especially if you consider older kernels that would simply ignore that
> new attribute.
> 
> So basically, the only difference between "trigger scan (scheduled=1)"
> and "trigger scheduled scan" (which this implements) would be in
> nl80211. Everything else would have to separate them, since there are a
> lot of internal things that behave differently depending on whether a
> scan is running or not. Add the error checking, and I think we've got a
> good case for new API :)

I agree.  I think it's better to keep it simpler with a new command.
Especially because the scheduled scan command will be extended with a
few more arguments, which may not make sense with normal scans, such as
filters etc.

-- 
Cheers,
Luca.