Re: [PATCH 01/13] wifi: cfg80211: Add provision to advertise multiple radio in one wiphy

[Vasanthakumar Thiagarajan <quic_vthiagar@quicinc.com>]

On 4/12/2024 1:08 PM, Nicolas Escande wrote:
> On Fri Apr 12, 2024 at 5:50 AM CEST, Vasanthakumar Thiagarajan wrote:
>>
>>
>> On 4/11/2024 10:09 PM, Maxime Bizon wrote:
>>>
>>> On Thu, 2024-04-11 at 21:56 +0530, Vasanthakumar Thiagarajan wrote:
>>>
>>> Hello,
>>>
>>> Thanks for making it clear,
>>>
>>>
>>>>> For example, starting a 5Ghz AP in ax-only mode, and at the same
>>>>> time
>>>>> creating a STA interface on 2.4GHz ?
>>>
>>>> Yes, such use cases continue to be supported in single wiphy mode.
>>>
>>> Understood, but I see some corner cases.
>>>
>>>
>>> For example, assume two bands AP hardware, 2.4GHz and 5GHz.
>>>
>>> Previously:
>>>     - phy0 is 2.4Ghz
>>>     - phy1 is 5Ghz
>>>     - iw phy phy0 interface create wlan0 type managed
>>>     - iw dev wlan0 scan
>>>
>>> => will only scan 2.4Ghz
>>>
>>>
>>> With single phy approach:
>>>     - phy0 is 2.4Ghz + 5Ghz concurrent
>>>     - # iw phy phy0 interface create wlan0 type managed
>>>     - # iw dev wlan0 scan
>>>
>>> => will scan both bands ?
>>>
>>
>> Yes, both the bands will be scanned if freq list is not given
>>
>>>     - <starting from previous state>
>>>     - # iw phy phy0 interface create wlan1 type __ap
>>>     - # hostapd -i wlan1 <config>
>>>     - # iw dev wlan0 scan
>>>
>>> => what will happen then ?
>>>
>>
>> Scan will be carried out on all the radios including the one on which AP interface is
>> running. Scan with freq list can be used not to disturb the radio of AP interface.
>>
>>>> Same goes for hostapd ACS, I assume specifying freqlist becomes
>>> mandatory or we can't predict which band the AP will be on ?
>>>
>>
>> If no freq list is given, ACS will run through all the bands and select a channel from any
>> of the bands. But this can be optimized to do ACS and channels selection on a particular
>> band using channellist/freqlist hostapd configurations.
> Hello,
> 
> And in a (very unlikely) case that there are two underlying radios that can
> operate on the same frequencies, how would freqlist enable us to really select
> the underlying radio ?
> 

This can not be supported in this approach. As only the radios participating in MLO are 
supposed to be combined under one wiphy, not sure if we have real use case to combine 
radios of same frequencies.

Vasanth