[PATCH] wpa_supplicant: Enable HT40 support for AP mode

[Rajkumar Manoharan]

On Mon, Jul 09, 2012 at 11:56:14AM +0300, Jouni Malinen wrote:
> On Mon, Jul 09, 2012 at 10:21:08AM +0530, Rajkumar Manoharan wrote:
> > Right now HT40 mode is not enabled for AP/P2P GO mode in wpa_supplicant.
> > If the HW is capable of 40MHz channel width and user specifies the
> > secondary channel posision, lets enable the HT40 mode in wpa_s. This
> > patch also enables HT40 support for P2P mode.
> > 
> > ap_ht40_mode : -1 -> HT40MINUS, 1 -> HT40PLUS
> 
> This looks quite confusing to use as a global parameter. The selection
> between HT40- and HT40+ should really be based on the channel that ends
> up getting used (e.g., cannot use HT40- on channel 36). The preferred
> way of specifying plus vs. minus would be with the operation that
> selects the channel (say, p2p_connect command). For a global parameter,
> I would rather have just enable_ht40 0/1 and have the plus/minus part
> figured out automatically based on which channel is going to be used.
>
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.

> > 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?

-Rajkumar