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Subject: Re: [PATCH 4/4] mt76: mt76x02: add channel switch support for usb
 interfaces
To:     Lorenzo Bianconi <lorenzo@kernel.org>
Cc:     nbd@nbd.name, linux-wireless@vger.kernel.org,
        lorenzo.bianconi@redhat.com,
        Stanislaw Gruszka <sgruszka@redhat.com>
References: <20191116111709.4686-1-markus.theil@tu-ilmenau.de>
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From:   Markus Theil <markus.theil@tu-ilmenau.de>
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Message-ID: <5dffcc2f-e722-395a-0077-1286f1c786b8@tu-ilmenau.de>
Date:   Sat, 16 Nov 2019 13:13:27 +0100
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Sender: linux-wireless-owner@vger.kernel.org
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On 11/16/19 12:45 PM, Lorenzo Bianconi wrote:
>> This patch enables channel switch support on mt76 usb interfaces.
>>
> Hi Markus,
>
> I was thinking about it, but since usb does not support DFS what is the purpose
> of CSA in this case?
>
> Regards,
> Lorenzo

Hi Lorenzo,

for research purposes I'm currently trying out some dynamic channel
allocation strategies with multiple indoor APs. I use a dedicated
interface to perform surveys and monitoring the environment. These
survey results are then correlated between different with traffic
patterns to find out interferers. Afterwards I let the AP interfaces
change their channel to a less congested one if necessary and notice the
STAs via CSAs.

I use mt76 based USB devices for my tests as they are quite versatile
and useful for debugging with a notebook (I can just attach multiple
ones). Therefore I thought, having the possibility to dynamically switch
channels on this devices would maybe useful to other researchers and
submitted my patches.

Regards,
Markus

>> Signed-off-by: Markus Theil <markus.theil@tu-ilmenau.de>
>> ---
>>  drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c | 7 +++++++
>>  drivers/net/wireless/mediatek/mt76/mt76x02_util.c     | 2 +-
>>  drivers/net/wireless/mediatek/mt76/mt76x2/usb_main.c  | 5 +++++
>>  3 files changed, 13 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c b/drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c
>> index aedab4cc8d40..32e6c37aa80d 100644
>> --- a/drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c
>> +++ b/drivers/net/wireless/mediatek/mt76/mt76x02_usb_core.c
>> @@ -179,6 +179,12 @@ static void mt76x02u_pre_tbtt_work(struct work_struct *work)
>>  
>>  	mt76x02_resync_beacon_timer(dev);
>>  
>> +	mt76_csa_check(&dev->mt76);
>> +	if (dev->mt76.csa_complete) {
>> +		mt76_csa_finish(&dev->mt76);
>> +		goto out;
>> +	}
>> +
>>  	mt76x02_mac_set_beacon_prepare(dev);
>>  
>>  	ieee80211_iterate_active_interfaces(mt76_hw(dev),
>> @@ -195,6 +201,7 @@ static void mt76x02u_pre_tbtt_work(struct work_struct *work)
>>  
>>  	mt76x02_mac_set_beacon_finish(dev);
>>  
>> +out:
>>  	mt76x02u_restart_pre_tbtt_timer(dev);
>>  }
>>  
>> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_util.c b/drivers/net/wireless/mediatek/mt76/mt76x02_util.c
>> index 414b22399d93..3f95e5b24e1d 100644
>> --- a/drivers/net/wireless/mediatek/mt76/mt76x02_util.c
>> +++ b/drivers/net/wireless/mediatek/mt76/mt76x02_util.c
>> @@ -174,7 +174,6 @@ void mt76x02_init_device(struct mt76x02_dev *dev)
>>  		wiphy->reg_notifier = mt76x02_regd_notifier;
>>  		wiphy->iface_combinations = mt76x02_if_comb;
>>  		wiphy->n_iface_combinations = ARRAY_SIZE(mt76x02_if_comb);
>> -		wiphy->flags |= WIPHY_FLAG_HAS_CHANNEL_SWITCH;
>>  
>>  		/* init led callbacks */
>>  		if (IS_ENABLED(CONFIG_MT76_LEDS)) {
>> @@ -184,6 +183,7 @@ void mt76x02_init_device(struct mt76x02_dev *dev)
>>  		}
>>  	}
>>  
>> +	wiphy->flags |= WIPHY_FLAG_HAS_CHANNEL_SWITCH;
>>  	wiphy_ext_feature_set(wiphy, NL80211_EXT_FEATURE_VHT_IBSS);
>>  
>>  	hw->sta_data_size = sizeof(struct mt76x02_sta);
>> diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/usb_main.c b/drivers/net/wireless/mediatek/mt76/mt76x2/usb_main.c
>> index eb73cb856c81..2f2c39a6a9e6 100644
>> --- a/drivers/net/wireless/mediatek/mt76/mt76x2/usb_main.c
>> +++ b/drivers/net/wireless/mediatek/mt76/mt76x2/usb_main.c
>> @@ -100,6 +100,10 @@ mt76x2u_config(struct ieee80211_hw *hw, u32 changed)
>>  	return err;
>>  }
>>  
>> +void mt76x2u_channel_switch_beacon(struct ieee80211_hw *hw,
>> +				   struct ieee80211_vif *vif,
>> +				   struct cfg80211_chan_def *chandef) {}
>> +
>>  const struct ieee80211_ops mt76x2u_ops = {
>>  	.tx = mt76x02_tx,
>>  	.start = mt76x2u_start,
>> @@ -121,4 +125,5 @@ const struct ieee80211_ops mt76x2u_ops = {
>>  	.get_survey = mt76_get_survey,
>>  	.set_tim = mt76_set_tim,
>>  	.release_buffered_frames = mt76_release_buffered_frames,
>> +	.channel_switch_beacon = mt76x2u_channel_switch_beacon,
>>  };
>> -- 
>> 2.24.0
>>
-- 
Markus Theil

Technische Universit?t Ilmenau, Fachgebiet Telematik/Rechnernetze
Postfach 100565
98684 Ilmenau, Germany

Phone: +49 3677 69-4582
Email: markus[dot]theil[at]tu-ilmenau[dot]de
Web: http://www.tu-ilmenau.de/telematik