[PATCH] wpa_supplicant: Enable HT40 support for AP mode

[Rajkumar Manoharan]

On Mon, Jul 09, 2012 at 09:36:22PM +0300, Jouni Malinen wrote:
> On Mon, Jul 09, 2012 at 03:13:23PM +0530, Rajkumar Manoharan wrote:
> > I thought of that too. But how about the channels that can operate in HT40+
> > and HT40- like channel 6. How can we determine that on which mode AP should
> > start with? So I followed the existing hostap approach.
> 
> Deciding something like this based on a global configuration parameter
> does not make much sense to me. If you need to specify HT40+ vs. HT40-
> (which would only be the case on some 2.4 GHz band channels), it should
> really be done as part of p2p_connect/p2p_group_add command parameters
> or as a network block parameter rather than global parameter.
>
Fine. I assume that ieee80211n_check_40mhz_2g4 always validates the scan results
before starting AP interface in HT40. Thats why i enabled it for both the bands.

For GO mode, we can use the p2p commands to enable 40MHz. But How about regular
(non-P2P) AP mode? Are we supporting traditional AP mode in wpa_s?

> > > > diff --git a/wpa_supplicant/p2p_supplicant.c b/wpa_supplicant/p2p_supplicant.c
> > > > @@ -2231,10 +2231,8 @@ static int wpas_p2p_setup_channels(struct wpa_supplicant *wpa_s,
> > > >  	struct p2p_oper_class_map op_class[] = {
> > > >  		{ HOSTAPD_MODE_IEEE80211G, 81, 1, 13, 1, BW20 },
> > > >  		{ HOSTAPD_MODE_IEEE80211G, 82, 14, 14, 1, BW20 },
> > > > -#if 0 /* Do not enable HT40 on 2 GHz for now */
> > > >  		{ HOSTAPD_MODE_IEEE80211G, 83, 1, 9, 1, BW40PLUS },
> > > >  		{ HOSTAPD_MODE_IEEE80211G, 84, 5, 13, 1, BW40MINUS },
> > > > -#endif
> > > 
> > > Why? 40 MHz channels on 2 GHz band were disabled on purpose and I would
> > > like to keep this separate from the possibility of using 40 MHz channels
> > > on 5 GHz.
> > If so, for 2GHz band alone cards we are not supporting HT40 in P2P mode.
> > Before starting in HT40 mode, we are already going though OBSS process.
> > Then why do we have to disable HT40 mode?
> 
> I would like to keep this change separate from the rest of the patch to
> keep these topics independent of each other. I have nothing against
> enabling 40 MHz channels on 5 GHz band for P2P use cases, but I'm not
> sure I would really like to see that as the default behavior for 2.4 GHz
> band. And even if ever enabled for 2.4 GHz, a more robust mechanism
> would be to first initiate the GO with 20 MHz channel and then switch to
> 40 MHz channel based on the co-existence procedure defined in 802.11n
> afterwards.
Fine.

-Rajkumar