From: Ben Greear <greearb@candelatech.com>
To: "Peer, Ilan" <ilan.peer@intel.com>, Luca Coelho <luca@coelho.fi>,
"kvalo@codeaurora.org" <kvalo@codeaurora.org>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH 06/12] iwlwifi: mvm: Add support for 6GHz passive scan
Date: Sun, 11 Apr 2021 04:16:58 -0700 [thread overview]
Message-ID: <eb60c152-81ac-2977-87fc-f724d4d6ccf0@candelatech.com> (raw)
In-Reply-To: <BN7PR11MB2610D9C80C698F837C3A2A55E9719@BN7PR11MB2610.namprd11.prod.outlook.com>
On 4/11/21 3:14 AM, Peer, Ilan wrote:
> Hi Ben,
>
>> -----Original Message-----
>> From: Ben Greear <greearb@candelatech.com>
>> Sent: Wednesday, March 31, 2021 15:04
>> To: Luca Coelho <luca@coelho.fi>; kvalo@codeaurora.org
>> Cc: linux-wireless@vger.kernel.org
>> Subject: Re: [PATCH 06/12] iwlwifi: mvm: Add support for 6GHz passive scan
>>
>> On 3/31/21 2:14 AM, Luca Coelho wrote:
>>> From: Ilan Peer <ilan.peer@intel.com>
>>>
>>> When doing scan while 6GHz channels are not enabled, the 6GHz band is
>>> not scanned. Thus, if there are no APs on the 2GHz and 5GHz bands
>>> (that will allow discovery of geographic location etc. that would
>>> allow enabling the 6GHz channels) but there are non collocated APs on
>>> 6GHz PSC channels these would never be discovered.
>>>
>>> To overcome this, FW added support for performing passive UHB scan in
>>> case no APs were discovered during scan on the 2GHz and 5GHz channels.
>>>
>>> Add support for enabling such scan when the following conditions are
>>> met:
>>>
>>> - 6GHz channels are supported but not enabled by regulatory.
>>> - Station interface is not associated or less than a defined time
>>> interval passed from the last resume or HW reset flows.
>>> - At least 4 channels are included in the scan request
>>> - The scan request includes the widlcard SSID.
>>> - At least 50 minutes passed from the last 6GHz passive scan.
>>
>> Why are you trying so hard to not do passive scans? This seems like it is set
>> up for all sorts of frustration.
>>
>
> This logic enables a special 'passive' scan which is not directly intended for discovery of APs for connection etc. but
> for discovery of APs with country information in the beacons/probe responses, so the fw could use this information
> as an input that might allow it to enable 6GHz channels (which are supported but are disabled). This special scan
> is intended for cases that the device does not have any other regulatory information that allows it to enable the 6GHz channels.
> Once these channels are enabled, we use passive scan as needed.
>
> We generally try to avoid passive scan on all the 6GHz channels as this is a long flow that takes at least 6 seconds (as there are
> such 64 channels) and with the discovery mechanisms defined for the 6GHz is not really needed.
If the station comes up and does a 6E passive scan and does not find any AP, perhaps because 6Ghz AP was turned on 1 minute after the station
tried to initially scan, this means that it will take 50 minutes before it can have a chance to scan
the AP and connect to the Internet? If station cannot connect after a relatively short time,
then I think it should scan as widely as it can in order find some possible way to connect.
And why care about 'at least 4 channels'. If we know the AP channel, and can scan exactly there, then your
concern about taking a long time is resolved.
How else can we tell the radio that 6E is allowed? I previously tried all sorts of things
to enable 6E channels so that I could more easily set the radio to sniff one of those channels
in monitor mode, and I had no luck.
If all of the 6E channels are marked as passive, what harm is it to enable the channels
in the regdom from the beginning?
Thanks,
Ben
>
> Hope this clarifies things.
>
> Regards,
>
> Ilan.
>
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
next prev parent reply other threads:[~2021-04-11 11:26 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-31 9:14 [PATCH 00/12] iwlwifi: updates intended for v5.13 2021-03-31 Luca Coelho
2021-03-31 9:14 ` [PATCH 01/12] iwlwifi: mvm: write queue_sync_state only for sync Luca Coelho
2021-04-12 10:24 ` Luca Coelho
2021-03-31 9:14 ` [PATCH 02/12] iwlwifi: mvm: clean up queue sync implementation Luca Coelho
2021-03-31 9:14 ` [PATCH 03/12] iwlwifi: mvm: when associated with PMF, use protected NDP ranging negotiation Luca Coelho
2021-03-31 9:14 ` [PATCH 04/12] iwlwifi: add ax201 killer device Luca Coelho
2021-03-31 9:14 ` [PATCH 05/12] iwlwifi: pcie: try to grab NIC access early Luca Coelho
2021-04-12 10:22 ` Luca Coelho
2021-03-31 9:14 ` [PATCH 06/12] iwlwifi: mvm: Add support for 6GHz passive scan Luca Coelho
2021-03-31 12:03 ` Ben Greear
2021-04-11 9:41 ` Luca Coelho
2021-04-11 10:14 ` Peer, Ilan
2021-04-11 11:16 ` Ben Greear [this message]
2021-04-11 12:14 ` Peer, Ilan
2021-04-11 16:15 ` Ben Greear
2021-04-13 12:49 ` Peer, Ilan
2021-03-31 9:14 ` [PATCH 07/12] iwlwifi: mvm: enable PPAG in China Luca Coelho
2021-03-31 9:14 ` [PATCH 08/12] iwlwifi: add new so-gf device Luca Coelho
2021-03-31 9:14 ` [PATCH 09/12] iwlwifi: move iwl_configure_rxq to be used by other op_modes Luca Coelho
2021-03-31 9:14 ` [PATCH 10/12] iwlwifi: mvm: support BIOS enable/disable for 11ax in Ukraine Luca Coelho
2021-03-31 9:14 ` [PATCH 11/12] iwlwifi: mvm: refactor ACPI DSM evaluation function Luca Coelho
2021-03-31 9:14 ` [PATCH 12/12] iwlwifi: mvm: Use IWL_INFO in fw_reset_handshake() Luca Coelho
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