Re: [PATCH ath-next v2] wifi: ath12k: combine channel list for split-phy devices in single-wiphy

[Rameshkumar Sundaram <rameshkumar.sundaram@oss.qualcomm.com>]

On 5/15/2025 12:04 PM, Kang Yang wrote:
> 
> 
> On 5/6/2025 6:56 PM, Rameshkumar Sundaram wrote:
>> When two split-phy devices that support overlapping frequency ranges 
>> within
>> the same band are grouped into an ath12k hardware (HW) setup, they 
>> share a
>> common wiphy instance. Consequently, the channel list (wiphy->bands[])
>> becomes unified across all associated radios (ar).
>>
>> For reference, the devices are:
>> 2.4 GHz + 5 GHz Low Band
>> 5 GHz High Band + 6 GHz
>>
>> The first radio probed within the 5 GHz range (say 5 GHz Low Band) 
>> updates
>> its sband reference (&ar->mac.sbands[NL80211_BAND_5GHZ]) within
>> wiphy->bands[]. However, when the second 5 GHz radio (5 GHz High Band) is
>> probed, it replaces the existing wiphy->bands[] entry with its own 
>> sub-band
>> reference. As a result, wiphy->bands[] always reflects the channel list
>> from the most recently probed radio in that band, restricting supported
>> channels to those within its specific range for upper-layer.
>>
>> Fix this by updating the wiphy->bands[] to just enable the channels of
>> current radio when there exist a radio which already has set it.
>> This will make sure wiphy->bands[] holds reference of first radio which
>> got probed in 5 GHz band and subsequent radio just updates the channel 
>> list
>> in the same address space.
>>
>> Since same sband memory space is shared between radios of a band, while
>> determining the allowed frequency range of radio, its frequency limits
>> (ar->freq_range.start_freq, end_freq) should be used.
>>
>> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1
> 
> 
> Offline sync with aditya:
> 
> This patch and patch [1][2] will make WCN7850 update regulatory rules 
> and trigger scan incorrectly.
> 
> They are based on the design that one chip only supports one band.
> 
> This design will limit WCN7850 to one band.
> During init, WCN7850 will be limited to one band(such as 5G band) due to 
> patch[1]. Then will only update 5G regulatory rules and trigger 5G scan.
> If manually set country code by "iw reg set XX", WCN7850 will be limited 
> to 2G band due to patch[2]. Then similar issue will happen.
> 
> 
> If QCN supports multi bands like WCN i think you will have the same 
> problem.
> 
> WIN team needs to figure a new design for this issue to support multi 
> bands on one chip too.
> 
> 
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/ath/ath.git/commit/? 
> h=pending&id=b7544de8a2984e61b95c58c1c6c1e8ce659b1021
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/ath/ath.git/commit/? 
> h=pending&id=13324cecbb2c390a11f1fbfe87f3a5e62d6e4591
> 
> 
> 

Thanks for pointing this out. we're working on a new change which fixes 
the frequency range marking in [1] & [2] for multi-band ar's, Will re 
base this patch on top it once it lands in public.

>>
>> Signed-off-by: Rameshkumar Sundaram 
>> <rameshkumar.sundaram@oss.qualcomm.com>
>> ---
>>
>> *v2:
>>    - Fixed frequency conversion from KHZ to MHZ in freq_to_idx()
>>
>> ---
>>   drivers/net/wireless/ath/ath12k/mac.c | 93 +++++++++++++++++++++++++--
>>   drivers/net/wireless/ath/ath12k/reg.c | 13 ++++
>>   drivers/net/wireless/ath/ath12k/wmi.c |  9 ++-
>>   3 files changed, 109 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/net/wireless/ath/ath12k/mac.c b/drivers/net/ 
>> wireless/ath/ath12k/mac.c
>> index 4dae941c9615..23cbf348e836 100644
>> --- a/drivers/net/wireless/ath/ath12k/mac.c
>> +++ b/drivers/net/wireless/ath/ath12k/mac.c
>> @@ -4131,8 +4131,9 @@ ath12k_mac_select_scan_device(struct 
>> ieee80211_hw *hw,
>>           band = NL80211_BAND_6GHZ;
>>       for_each_ar(ah, ar, i) {
>> -        /* TODO 5 GHz low high split changes */
>> -        if (ar->mac.sbands[band].channels)
>> +        if (ar->mac.sbands[band].channels &&
>> +            center_freq >= KHZ_TO_MHZ(ar->freq_range.start_freq) &&
>> +            center_freq <= KHZ_TO_MHZ(ar->freq_range.end_freq))
> 
> 
> Though WCN7850 won't reach here, but this is also not good for those 
> chips who support multi bands.