On Tue, 2015-10-13 at 23:24 -0700, Grant Erickson wrote:
> Due to these constraints, the application knows best when to scan and
> does so at its discretion. Neither connman nor wpa_s autoscan
> infrastructure scan at the application-desired times. When they do
> scan automatically, it typically results in one or both of an
> undesirable expenditure of power or a momentary and inopportune move
> off-channel.

Fair enough. There is always the BackgroundScanning option in main.conf
that you then should set to false in order not to have ConnMan
restarting autoscans for no apparent benefit and an undesired increase
in at least power consumption.

Notice that support for wpa_supplicant's internal autoscan mechanism was
removed a while back in version 1.28, as it interfered with hidden SSID
detection. Nowadays only ConnMan's internal autoscan implementation is
being used.

> Absent the proposed change, per doc/overview-api.txt, with a WiFi
> network continually refreshed, there is no exit path from the Failure
> service state and, consequently, no unattended means by which the
> application can recover WiFi connectivity under these circumstances in
> a deterministic and application-controlled way.

Since the application has full knowledge of what the suitable scan
interval is for this device, there is really no reason why the
application cannot issue a Connect() as well after a finished scan. This
way the application can gracefully get away from situations where
previous service connect attempts failed. This also works should the
application have had a need to disconnect the service in between.

> The proposed change offers, for unattended applications that wish to
> avail themselves of it, an exit gate to effectively acknowledge a
> service error by clearing it. There is no downside or consequence to
> interactive applications that wish to continue to operate as they do
> today.

If the application already knows better when to scan, it also knows
better when to issue a reconnect. Opening up service state transitions
to user or UI interference is a can of worms I cannot maintain in any
sensible manner. Autoscan backoff strategy and wifi network expiry are
up for tweaking to better values, but here one needs to come with an
explanation how everything functions smoother afterwards.



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