Re: [PATCH] wifi: ath12k: Remove broken frequency range filtering

[Baochen Qiang <baochen.qiang@oss.qualcomm.com>]

On 1/26/2026 2:35 PM, Saikiran B wrote:
> Hi Baochen,
> 
> Thanks for the review.
> 
> regarding ath12k_mac_update_freq_range(): You are correct that this
> function eventually updates the frequency range.
> 
> However, on the WCN7850 (Lenovo Yoga Slim 7x), there is a race condition
> during boot/resume. ath12k_reg_update_chan_list() is being executed *before*
> ath12k_regd_update() has finished populating ar->freq_range.

could you please elaborate on the race?

> 
> At that specific moment, ar->freq_range.end_freq is still 0. The check: if
> (center_freq > KHZ_TO_MHZ(ar->freq_range.end_freq)) evaluates to true for
> all channels, causing the driver to silently drop every 5GHz channel from
> the scan list.
> 
> If I cannot remove this filter entirely, would you accept a V2 that skips
> the filtering if the range is uninitialized?
> 
> Example:
> 
> /* Skip check if regulatory range hasn't been populated yet */if
> (ar->freq_range.end_freq != 0 &&
>     (center_freq < KHZ_TO_MHZ(ar->freq_range.start_freq) ||
>      center_freq > KHZ_TO_MHZ(ar->freq_range.end_freq)))
>         continue;
> 
> Without this change (or something similar), 5GHz is completely unusable on
> this platform.
> 
> Thanks & Regards,
> Jaya saikiran
> 
> On Mon, Jan 26, 2026 at 11:15 AM Baochen Qiang <
> baochen.qiang@oss.qualcomm.com> wrote:
> 
>>
>>
>> On 1/23/2026 11:57 PM, Saikiran wrote:
>>> Between kernel 6.16 and 6.17, ath12k added frequency range filtering in
>>> ath12k_reg_update_chan_list() that filters channels based on
>>> ar->freq_range.start_freq and ar->freq_range.end_freq.
>>>
>>> However, these values are reset to 0 in ath12k_regd_update(), causing
>>
>> Yes, it is reset at the first, but it get re-calculated later. See
>> ath12k_mac_update_freq_range() called in ath12k_regd_update().
>>
>>> the filter to skip ALL channels:
>>>     if (channel_freq < 0 || channel_freq > 0)  // Always true when
>> end_freq=0
>>>         continue;  // All channels skipped
>>>
>>> This results in no channel list sent to firmware, causing 5 GHz Wi-Fi
>>> to stop working.
>>>
>>> Fix by removing the broken frequency range filtering. The firmware
>>> itself handles frequency range restrictions based on hardware
>> capabilities.
>>>
>>> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00302 (Lenovo Yoga Slim 7x)
>>>
>>> Signed-off-by: Saikiran <bjsaikiran@gmail.com>
>>> ---
>>>  drivers/net/wireless/ath/ath12k/reg.c | 13 -------------
>>>  1 file changed, 13 deletions(-)
>>>
>>> diff --git a/drivers/net/wireless/ath/ath12k/reg.c
>> b/drivers/net/wireless/ath/ath12k/reg.c
>>> index 2dfcef013277..2d9adc74ac6e 100644
>>> --- a/drivers/net/wireless/ath/ath12k/reg.c
>>> +++ b/drivers/net/wireless/ath/ath12k/reg.c
>>> @@ -153,12 +153,6 @@ int ath12k_reg_update_chan_list(struct ath12k *ar,
>> bool wait)
>>>                       if (bands[band]->channels[i].flags &
>>>                           IEEE80211_CHAN_DISABLED)
>>>                               continue;
>>> -                     /* Skip Channels that are not in current radio's
>> range */
>>> -                     if (bands[band]->channels[i].center_freq <
>>> -                         KHZ_TO_MHZ(ar->freq_range.start_freq) ||
>>> -                         bands[band]->channels[i].center_freq >
>>> -                         KHZ_TO_MHZ(ar->freq_range.end_freq))
>>> -                             continue;
>>>
>>>                       num_channels++;
>>>               }
>>> @@ -190,13 +184,6 @@ int ath12k_reg_update_chan_list(struct ath12k *ar,
>> bool wait)
>>>                       if (channel->flags & IEEE80211_CHAN_DISABLED)
>>>                               continue;
>>>
>>> -                     /* Skip Channels that are not in current radio's
>> range */
>>> -                     if (bands[band]->channels[i].center_freq <
>>> -                         KHZ_TO_MHZ(ar->freq_range.start_freq) ||
>>> -                         bands[band]->channels[i].center_freq >
>>> -                         KHZ_TO_MHZ(ar->freq_range.end_freq))
>>> -                             continue;
>>> -
>>>                       /* TODO: Set to true/false based on some
>> condition? */
>>>                       ch->allow_ht = true;
>>>                       ch->allow_vht = true;
>>
>>
>