Hi Johannes, This is because that OBSS scan happens before starting AP and ACS happens within start_ap.
Thanks, Peng -----Original Message----- From: Johannes Berg [mailto:[email protected]] Sent: Thursday, October 09, 2014 11:41 AM To: Xu, Peng Cc: Park, Kyeyoon; cfg80211mac80211; [email protected] Subject: Re: [PATCH] cfg80211: Add support for ACS offloading On Thu, 2014-10-09 at 17:38 +0000, Xu, Peng wrote: > This change is originated from a problem caused by OBSS scan and ACS > feature in the driver. When SAP is started, hostapd will do an OBSS > scan based on the channel setting in hostapd.conf, if the wlan driver > has the ACS capability, it may choose a different channel. Even it > notifies hostapd about the channel selection, the OBSS scan result may > become invalid if a different channel is selected and SAP may end up > operating in not desired mode. > This change will allow the wlan driver do the ACS and decide a > channel, once hostapd is notified, it can then do OBSS scan using that > channel. ACS operation is done during SAP starting up, beacon is sent > after channel is selected by driver. All of this may be true, but I was asking why this has to be part of START_AP, and that's not answering that question. johannes
