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Date: Wed, 12 Jun 2024 16:29:57 +0200
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Subject: Re: [RFC v3 4/8] wifi: mac80211: add support for DFS with multiple
 radios
To: Karthikeyan Periyasamy <quic_periyasa@quicinc.com>,
 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>
 <3483a69d-6918-c91c-6349-7f268fe44e15@quicinc.com>
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From: Felix Fietkau <nbd@nbd.name>
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In-Reply-To: <3483a69d-6918-c91c-6349-7f268fe44e15@quicinc.com>
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On 12.06.24 16:23, 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
>> @@ -1084,6 +1084,21 @@ static int ieee80211_init_cipher_suites(struct ieee80211_local *local)
>>   	return 0;
>>   }
>>   
>> +static bool
>> +ieee80211_ifcomb_check_radar(const struct ieee80211_iface_combination *comb,
>> +			     int n_comb)
>> +{
>> +	int i;
>> +
>> +	/* DFS is not supported with multi-channel combinations yet */
>> +	for (i = 0; i < n_comb; i++, comb++)
>> +		if (comb->radar_detect_widths &&
>> +		    comb->num_different_channels > 1)
>> +			return false;
>> +
>> +	return true;
>> +}
>> +
>>   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;
>>   		}
> 
> When driver advertise per radio iface combination, you are not checking
> the global iface combination. using the uncheck global iface combination
> lead to unknown issues.

The only constraint being checked here is num_different_channel > 1 XOR 
comb->radar_detect_widths != 0.
The global wiphy needs both being set, since it applies the sum of all 
radios. For each individual radio, the constraint is enforced, so there 
should not be any unknown issues.

- Felix