Subject: Re: [PATCH ath-next] wifi: ath12k: avoid setting 320MHZ support on non 6GHz band

From: "Nicolas Escande" <[email-masked]>
Date: Mon, 01 Jun 2026 19:08:48 +0200

On Thu May 28, 2026 at 9:56 AM CEST, Rameshkumar Sundaram wrote:
> On 1/23/2026 8:12 PM, Nicolas Escande wrote:
>> On a split phy qcn9274 (2.4GHz + 5GHz low), "iw phy" reports 320MHz
>> realated features on the 5GHz band while it should not:
>> 
>>      Wiphy phy1
>>      [...]
>>          Band 2:
>>      [...]
>>              EHT Iftypes: managed
>>      [...]
>>                  EHT PHY Capabilities: (0xe2ffdbe018778000):
>>                      320MHz in 6GHz Supported
>>      [...]
>>                      Beamformee SS (320MHz): 7
>>      [...]
>>                      Number Of Sounding Dimensions (320MHz): 3
>>      [...]
>>                  EHT MCS/NSS: (0x22222222222222222200000000):
>> 
>> This is also reflected in the beacons sent by a mesh interface started on
>> that band. They erroneously advertise 320MHZ support too.
>> 
>> This should not happen as the spec at section 9.4.2.323.3 says we should
>> not set the 320MHz related fields when not operating on a 6GHz band.
>> For example it says about Bit 0 "Support For 320 MHz In 6 GHz"
>> 
>>    "Reserved if the EHT Capabilities element is indicating capabilities for
>>     the 2.4 GHz or 5 GHz bands."
>> 
>> Fix this by clearing the related bits when converting from WMI eht phy
>> capabilities to mac80211 phy capabilities, for bands other than 6GHz.
>> 
>> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00218-QCAHKSWPL_SILICONZ-1
>> 
>> Signed-off-by: Nicolas Escande <[email-masked]>
>> ---
>>   drivers/net/wireless/ath/ath12k/wmi.c | 9 ++++++++-
>>   1 file changed, 8 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/net/wireless/ath/ath12k/wmi.c b/drivers/net/wireless/ath/ath12k/wmi.c
>> index 84c29e4896a4..14947fdb9813 100644
>> --- a/drivers/net/wireless/ath/ath12k/wmi.c
>> +++ b/drivers/net/wireless/ath/ath12k/wmi.c
>> @@ -4888,6 +4888,7 @@ static void ath12k_wmi_eht_caps_parse(struct ath12k_pdev *pdev, u32 band,
>>   				       __le32 cap_info_internal)
>>   {
>>   	struct ath12k_band_cap *cap_band = &pdev->cap.band[band];
>> +	u8 *phy_cap = (u8 *)&cap_band->eht_cap_phy_info[0];
>>   	u32 support_320mhz;
>>   	u8 i;
>>   
>> @@ -4901,8 +4902,14 @@ static void ath12k_wmi_eht_caps_parse(struct ath12k_pdev *pdev, u32 band,
>>   	for (i = 0; i < WMI_MAX_EHTCAP_PHY_SIZE; i++)
>>   		cap_band->eht_cap_phy_info[i] = le32_to_cpu(cap_phy_info[i]);
>>   
>> -	if (band == NL80211_BAND_6GHZ)
>> +	if (band == NL80211_BAND_6GHZ) {
>>   		cap_band->eht_cap_phy_info[0] |= support_320mhz;
>> +	} else {
>> +		phy_cap[0] &= ~IEEE80211_EHT_PHY_CAP0_320MHZ_IN_6GHZ;
>> +		phy_cap[1] &= ~IEEE80211_EHT_PHY_CAP1_BEAMFORMEE_SS_320MHZ_MASK;
>> +		phy_cap[2] &= ~IEEE80211_EHT_PHY_CAP2_SOUNDING_DIM_320MHZ_MASK;
>
> This field is split across PHY capability byte 2 and byte 3, so should
> IEEE80211_EHT_PHY_CAP3_SOUNDING_DIM_320MHZ_MASK be cleared as well ?

Indeed

>
>
>> +		phy_cap[6] &= ~IEEE80211_EHT_PHY_CAP6_MCS15_SUPP_320MHZ;
>> +	}
>>   
>>   	cap_band->eht_mcs_20_only = le32_to_cpu(supp_mcs[0]);
>>   	cap_band->eht_mcs_80 = le32_to_cpu(supp_mcs[1]);
>
>
> Since you said "On a split phy qcn9274 (2.4GHz + 5GHz low)" i wonder how 
> firmware set 6GHz capability bits in this case. That said, the approach 

I suspect that the firmware sets the same features for mode 'a', regardless of
the actual frequency range supported by the device. I've also seen this on a
5G + 6G split device too.

> looks fine to me, although I would prefer to clear the remaining related 
> bits as well:
>
>    IEEE80211_EHT_PHY_CAP3_SOUNDING_DIM_320MHZ_MASK
>    IEEE80211_EHT_PHY_CAP6_MCS15_SUPP_320MHZ
>    IEEE80211_EHT_PHY_CAP6_EHT_DUP_6GHZ_SUPP
>    IEEE80211_EHT_PHY_CAP7_NON_OFDMA_UL_MU_MIMO_320MHZ
>    IEEE80211_EHT_PHY_CAP7_MU_BEAMFORMER_320MHZ

Yes, I cleared the ones I used in my middleware but I really don't mind
clearing all the 6GHz/320MHz related bits I can find.

Thanks for the review, I'll spin a v2