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Date: Mon, 13 Aug 2012 11:05:54 +0530
Message-ID: <CAD2nsn11JdqNueAjhGxxvkAJ_BTex5Sropqo93odiOmj1bzpLQ@mail.gmail.com> (sfid-20120813_073637_223558_36263D82)
Subject: Re: [cfg80211] Issue with simultaneous AP-STA operation in mwifiex/cfg80211
From: Mohammed Shafi <shafi.wireless@gmail.com>
To: Avinash Patil <avinashapatil@gmail.com>
Cc: linux-wireless@vger.kernel.org, Avinash Patil <patila@marvell.com>,
	Bing Zhao <bzhao@marvell.com>,
	Kiran Divekar <dkiran@marvell.com>
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Sender: linux-wireless-owner@vger.kernel.org

Hi,


On Fri, Aug 10, 2012 at 11:37 AM, Avinash Patil <avinashapatil@gmail.com> wrote:
> Hi All,
>
> Lately simultaneous AP-STA functionality in mwifiex driver is not
> working. I feel this has something to do with recent changes in
> cfg80211.
>
> If we associate mwifiex STA to external AP first and then try to start
> mwifiex AP using hostapd(on different channel), we get ?EBUSY error
> from cfg80211. This happens from path
> nl80211_start_ap->cfg80211_can_use_chan.  cfg80211_can_use_chan
> returns EBUSY error. In our design if mwifiex STA is already
> associated on some different channel, AP follows this channel and BSS
> is started using STA channel settings. If we start hostapd on same
> channel, BSS is successfully started, but association requests from
> external station result in failure.


i got the same EBUSY error when i tried to start a P2P-GO in a different
channel when my other concurrent STA is associated to some other channel.
first cfg80211_can_use_chan ->  cfg80211_can_use_iftype_chan
when driver advertises num_different_channels as 1
it seems to be caught under the following logic

  case CHAN_MODE_SHARED:
1077                         for (i = 0; i <
CFG80211_MAX_NUM_DIFFERENT_CHANNELS; i++)
1078                                 if (!used_channels[i] ||
used_channels[i] == ch)
1079                                         break;
1080
1081                         if (i == CFG80211_MAX_NUM_DIFFERENT_CHANNELS)
1082                                 return -EBUSY;
1083
1084                         if (used_channels[i] == NULL) {
1085                                 used_channels[i] = ch;
1086                                 num_different_channels++;
1087                         }
1088                         break;

used_channels[1] is NULL
num_different_channels becomes '2' when STA vifs is already in some
other channel

the following check in interface_combination for loop seems to cause
the EBUSY error

1111                 if (num_different_channels > c->num_different_channels)
1112                         continue;

not sure why assoc req from external STA fails.


>
> Please let me know if we are missing something while registering
> n_iface and iface combinations. num_different_channels in
> ieee80211_iface_combination has been advertised as 1.
>
> Regards,
> Avinash.
> --
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-- 
thanks,
shafi