Re: Prevent auto scan in wireless devices (Aloisio Almeida)

[Howard Chu <hyc symas com>]

> Date: Tue, 13 Jan 2009 17:45:16 -0300
> From: Aloisio Almeida<aloisio almeida openbossa org>

> Hi all,
>
> I noticed that wireless devices are always scanning, and this is very
> bad to power consuption in embedded systems.
> I would like to create a way to prevent automatic scan and just
> perform it when some cliente ask for it.
> Is it possible to do this? I mean, does it "brake" in some way the nm structure?
>
> Actually, I already did this patch to 0.6.6 version, but zero lines
> applied in new code :) Now i would like to create the patch and submit
> to upstream.
>
> The basic idea is just make can_scan function (src/nm-device-wifi.c)
> return FALSE due to some user configurations or run flags
> (--no-bg-scan). In this case, "performScan" dbus method and
> "ScanPerformed" dbus signal must be created to allow clients to ask
> for a scan and to notice that the scan has been performed.
>
> I'm attaching the 0.6.6 patch, as I said before the idea is the same.
>
> Any comments? Is it a good way to implement that?

I also noticed that in NM 0.7 prereleases, scans did not occur on my ath9k 
when it was associated, but after 0.7 was released, this behavior changed. (I 
found the commit that changed this, saying it was removing a hack...) I 
reinstated the hack on my build, because it was disrupting my streaming wifi 
traffic. All in all, I would love to see scans only occurring on demand, and 
not at any other time.
--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/