[PATCH] Enabling 802.11ac (VHT) mode

Jose Blanquicet blanquicet at gmail.com
Mon Jul 25 02:19:51 PDT 2016

Hi Jouni,

Thanks for your feedback.

On Sat, Jul 23, 2016 at 7:22 PM, Jouni Malinen <j at w1.fi> wrote:
> On Mon, Jun 13, 2016 at 04:53:08PM +0200, Jose Blanquicet wrote:
> > When an AP is trying to be enabled in 802.11ac (VHT) mode by setting its
> > parameter disable_vht to 0, it is not actually enabled and it's set to HT.
> >
> > Looking at the source code it was found that the variable used to check
> > whether to enable or not the VHT is ssid->vht but it has not been set
> > before. Instead, the variable ssid->disable_vht stores the actual network
> > parameter which indicates if the VHT has been disabled or not.
> >
> > Is it OK? Or there is something I am missing to correctly set wpa_supplicant
> > in AC mode?
> ssid->vht is used when setting up a P2P GO. However, it looks like the
> configuration parser does not provide means for enabling this for
> non-P2P use cases (i.e., when setting up an AP mode operation with
> wpa_supplicant).

You are right, I didn't take into account P2P-GO.

I used the following network configuration, is something missing?


set_network 0 ssid "Marvell-AP"
set_network 0 psk "01234567"
set_network 0 mode 2
set_network 0 proto RSN
set_network 0 key_mgmt WPA-PSK
set_network 0 frequency 5180
set_network 0 disable_vht 0
set_network 0 disable_ht 0

select_network 0

> > diff --git a/wpa_supplicant/ap.c b/wpa_supplicant/ap.c
> > @@ -166,7 +166,7 @@ int wpa_supplicant_conf_ap_ht(struct wpa_supplicant *wpa_s,
> > -                     if (mode->vht_capab && ssid->vht) {
> > +                     if (mode->vht_capab && !ssid->disable_vht) {
> >                               conf->ieee80211ac = 1;
> >                               wpas_conf_ap_vht(wpa_s, conf, mode);
> >                       }
> This would break builds without CONFIG_VHT_OVERRIDES defined. In
> addition, this would break the expected P2P behavior on how VHT is being
> enabled. I guess it could be fine to make the non-P2P AP case enable VHT
> automatically based on driver capabilities (and allow that to be
> prevented that with ssid->disable_vht).

Also true, it will not work without CONFIG_VHT_OVERRIDES definition.

Enabling VHT by default if it is available is the best idea. In fact,
according to comments in config_ssid.h, that should be the normal
behavior: "By default, use it (disable_vht) if it is available, but
this can be configured to 1 to have it disabled.".
Therefore, I used iwconfig to check which capabilities my driver
reports and I saw "IEEE 802.11-DS". Looking on Internet for it, I
found an old discussion on this mailing-list where you answered that
IEEE 802.11-DS could be caused by an error inside firmware. I think
this could be the reason I haven't been able to enable AP in VHT mode,
wpa_supplicant is not aware my chip supports VHT. How could I confirm
this? What do you suggest?

Thanks for you help!

Best regards,

Jose Blanquicet

> --
> Jouni Malinen                                            PGP id EFC895FA

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