Re: [PATCH] cfg80211: fix regression on beacon world roaming feature

Johannes Berg
2009-07-31T17:52:35Z

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On Thu, 2009-07-30 at 17:43 -0700, Luis R. Rodriguez wrote:
> A regression was added through patch a4ed90d6:
>
> "cfg80211: respect API on orig_flags on channel for beacon hint"
>
> We did indeed respect _orig flags but the intention was not clearly
> stated in the commit log. This patch fixes firmware issues picked
> up by iwlwifi when we lift passive scan of beaconing restrictions
> on channels its EEPROM has been configured to always enable.
>
> By doing so though we also disallowed beacon hints on devices
> registering their wiphy with custom world regulatory domains
> enabled, this happens to be currently ath5k, ath9k and ar9170.
> The passive scan and beacon restrictions on those devices would
> never be lifted even if we did find a beacon and the hardware did
> support such enhancements when world roaming.
>
> Since Johannes indicates iwlwifi firmware cannot be changed to
> allow beacon hinting we set up a flag now to specifically allow
> drivers to disable beacon hints for devices which cannot use them.
>
> We enable the flag on iwlwifi to disable beacon hints and by default
> enable it for all other drivers. It should be noted beacon hints lift
> passive scan flags and beacon restrictions when we receive a beacon from
> an AP on any 5 GHz non-DFS channels, and channels 12-14 on the 2.4 GHz
> band. We don't bother with channels 1-11 as those channels are allowed
> world wide.
>
> This should fix world roaming for ath5k, ath9k and ar9170, thereby
> improving scan time when we receive the first beacon from any AP,
> and also enabling beaconing operation (AP/IBSS/Mesh) on cards which
> would otherwise not be allowed to do so. Drivers not using custom
> regulatory stuff (wiphy_apply_custom_regulatory()) were not affected
> by this as the orig_flags for the channels would have been cleared
> upon wiphy registration.

Ok, so after all the discussion this seems like the best option after
all.

Reviewed-by: Johannes Berg <johannes@sipsolutions.net>

except I'm not sure about this bit:

> chan->beacon_found = true;
>
> + if (wiphy->disable_beacon_hints)
> + return;

seems like the if might need to be before beacon_found=true?

johannes

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