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Message-ID: <d2d93a48-e8f9-eb4c-7914-5886f60fad65@quicinc.com>
Date: Fri, 7 Jun 2024 14:24:28 +0530
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Subject: Re: [RFC v3 4/8] wifi: mac80211: add support for DFS with multiple
 radios
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To: Felix Fietkau <nbd@nbd.name>, <linux-wireless@vger.kernel.org>
CC: <johannes@sipsolutions.net>, <quic_adisi@quicinc.com>,
        <ath12k@lists.infradead.org>
References: <cover.386a66ec6a89750d4890f63f0d28582a52b838b5.1717696995.git-series.nbd@nbd.name>
 <7cc3d89225f365c85b363874725cfbc77c9c1db5.1717696995.git-series.nbd@nbd.name>
 <2014e488-b930-43ff-86a6-c5a4801b82f5@quicinc.com>
 <21956735-3a04-4f29-8f13-0f84ed93cda2@nbd.name>
 <cdf2d06a-4d06-df69-245b-fc9ece0c1f2b@quicinc.com>
 <da6038ed-87f8-40ec-a327-6065334097af@nbd.name>
 <6704d2ba-8ac8-cd33-9d3b-95dae2613d9f@quicinc.com>
 <80aed11e-12be-472a-8664-1bd1e6dce8f3@nbd.name>
From: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>
In-Reply-To: <80aed11e-12be-472a-8664-1bd1e6dce8f3@nbd.name>
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On 6/7/2024 1:46 PM, Felix Fietkau wrote:
> On 07.06.24 08:45, Karthikeyan Periyasamy wrote:
>>
>>
>> On 6/7/2024 10:33 AM, Felix Fietkau wrote:
>>> On 07.06.24 06:54, Karthikeyan Periyasamy wrote:
>>>>
>>>>
>>>> On 6/7/2024 10:05 AM, Felix Fietkau wrote:
>>>>> On 07.06.24 06:25, Karthikeyan Periyasamy wrote:
>>>>>>
>>>>>>
>>>>>> On 6/6/2024 11:37 PM, Felix Fietkau wrote:
>>>>>>> DFS can be supported with multi-channel combinations, as long as 
>>>>>>> each DFS
>>>>>>> capable radio only supports one channel.
>>>>>>>
>>>>>>> Signed-off-by: Felix Fietkau <nbd@nbd.name>
>>>>>>> ---
>>>>>>>   net/mac80211/main.c | 32 ++++++++++++++++++++++++--------
>>>>>>>   1 file changed, 24 insertions(+), 8 deletions(-)
>>>>>>>
>>>>>>> diff --git a/net/mac80211/main.c b/net/mac80211/main.c
>>>>>>> index 40fbf397ce74..e9c4cf611e94 100644
>>>>>>> --- a/net/mac80211/main.c
>>>>>>> +++ b/net/mac80211/main.c
>>>>>>
>>>>>> ...
>>>>>>
>>>>>>>   int ieee80211_register_hw(struct ieee80211_hw *hw)
>>>>>>>   {
>>>>>>>       struct ieee80211_local *local = hw_to_local(hw);
>>>>>>> @@ -1173,17 +1188,18 @@ int ieee80211_register_hw(struct 
>>>>>>> ieee80211_hw *hw)
>>>>>>>               if (comb->num_different_channels > 1)
>>>>>>>                   return -EINVAL;
>>>>>>>           }
>>>>>>> -    } else {
>>>>>>> -        /* DFS is not supported with multi-channel combinations 
>>>>>>> yet */
>>>>>>> -        for (i = 0; i < local->hw.wiphy->n_iface_combinations; 
>>>>>>> i++) {
>>>>>>> -            const struct ieee80211_iface_combination *comb;
>>>>>>> -
>>>>>>> -            comb = &local->hw.wiphy->iface_combinations[i];
>>>>>>> +    } else if (hw->wiphy->n_radio) {
>>>>>>> +        for (i = 0; i < hw->wiphy->n_radio; i++) {
>>>>>>> +            const struct wiphy_radio *radio = &hw->wiphy->radio[i];
>>>>>>> -            if (comb->radar_detect_widths &&
>>>>>>> -                comb->num_different_channels > 1)
>>>>>>> +            if 
>>>>>>> (!ieee80211_ifcomb_check_radar(radio->iface_combinations,
>>>>>>> +                              radio->n_iface_combinations))
>>>>>>>                   return -EINVAL;
>>>>>>>           }
>>>>>>> +    } else {
>>>>>>> +        if 
>>>>>>> (!ieee80211_ifcomb_check_radar(hw->wiphy->iface_combinations,
>>>>>>> +                          hw->wiphy->n_iface_combinations))
>>>>>>> +            return -EINVAL;
>>>>>>>       }
>>>>>>>       /* Only HW csum features are currently compatible with 
>>>>>>> mac80211 */
>>>>>>
>>>>>> Are we omitting the "wiphy->iface_combinations" if the radio specific
>>>>>> iface combination advertised ?
>>>>>>
>>>>>> If so, it looks like unused "wiphy->iface_combinations" for radio
>>>>>> specific combination advertised.
>>>>>
>>>>> This patch series assumes that you have both 
>>>>> wiphy->iface_combinations and radio->iface_combinations set. 
>>>>> wiphy->iface_combinations applies to the full wiphy, whereas 
>>>>> radio->iface_combinations only applies to vifs assigned to the radio.
>>>>
>>>>
>>>> If radio->iface_combinations is set then always vifs assigned to the
>>>> radio. so wiphy->iface_combinations get avoid for all the use cases.
>>>>
>>>> Ultimately either of one combination only get used by this proposal.
>>>>
>>>> or I am missing something here ?
>>>
>>> The functions that perform interface combination checks are called 
>>> both with -1 as radio_idx (meaning per-wiphy), as well as with the 
>>> assigned radio id. That way, both kinds of combinations/limits are 
>>> checked and enforced.
>>>
>> In the radio specific iface advertisement, global iface combination
>> represent the union or intersection of all radio iface combination ?
> 
> The global interface combination should be a union of all radio 
> interface combinations.
> You can also use them to apply extra limits, e.g. if you have a limit on 
> the per-wiphy number of interfaces (regardless of the assigned radio), 
> you use the global interface combination to apply it.
> 
If the global combination follow union representation, the non-ML client 
takes wrong/invalid perception against the global advertisement.

Ex:

Global iface = 14 ( Radio iface: 2G = 4, 5G = 4, 6G = 6 ).

2G non-client read the global configuration and understand it can able 
to create 14 interfaces. But in reality it allowed to create max 4 
interface only.

we have to follow intersection or minimal set, no ?


-- 
Karthikeyan Periyasamy
--
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