for these chipsets.
* Correctly set the active/passive flag in the scan request - this is
NOT a "is the channel active|passive"; it's to do with whether we
have an SSID to actively scan for or not. The firmware takes care
of the active/passive setup of the channel.
* Calculate the active/passive dwell time based on the beacon interval
and the channel mode, rather than using a hard coded value.
* For now, hardcode the scan service_time. It's defined as:
31:22 - number of beacon intervals to come back onto the home channel
for;
0:21 - time (microseconds) to come back onto the home channel for.
When doing an active scan when the NIC is active (whether we're associated
or not - it only matters if we've setup the NIC to a destination or not)
this determines how much time to stay on the home channel for when
scanning. We can tune this based on the amount of active traffic.
For now it's 4 beacon intervals and 100 microseconds.
* Fix the "good crc threshold" setting. It differs based on the NIC
firmware. Some older firmware required a workaround; the later
firmware instead treats the field as a flag.
* Enforce that we are not sending a scan command if one is already
pending. Any time this is done is a bug and it absolutely needs
to be fixed - so be very loud.
* Add the SCAN flag to a few debug messages that are scan related but
only occuring under STATE.
Now, this does get noisy when you're scanning in an actively busy 2GHz
network as the firmware (for reason I don't quite yet understand) seems
hell bent on staying on some passive channels longer than it should.
However, it should eventually recover and complete the scan.
This is a work in progress; please let me know if things get stuck or
if things improve!
Tested:
* intel centrino 2200
* intel centrino 2230
* intel 6200
* intel 5100
* intel 4965 (gets upset, but that's a known issue)
Obtained from: linux iwlwifi
fee842aa2a