Lose AP-STA connection on changing channel width

Hello Developers!

I am trying to change channel type/width (HT20/HT40+) on the both STA
and AP side in a simple system consists of only 1 STA and the AP.

AP is started using hostapd under HT20 and STA thereafter connects to
it using also HT20. But when AP changes its channel type to HT40+
using ieee80211_set_channel_type() and ath9k_hw_set_channel_regs(), it
will lose connection to STA. The way I do channel type change
coordination is: STA sends an action frame to AP, AP sends back ACK
frame and changes its channel type; STA changes its channel type on
receiving the ACK.

I read about this solution
(http://eznemegy.blog.hu/2008/12/14/using_rt2x00_wireless_driver_with_hostapd/fullcommentlist/1)
of hacking into hostapd, which didn't work...

It would be great if you more experienced would love to help me with
this problem!

Thanks in advance!!
Zhe