Message-ID: <10e4b6bf-f375-e50f-063a-b44471359d25@quicinc.com>
Date:   Fri, 24 Feb 2023 15:38:23 +0530
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Subject: Re: [PATCH] wifi: ath11k: Optimize 6 GHz scan time
To:     James Prestwood <prestwoj@gmail.com>,
        Marcel Holtmann <marcel@holtmann.org>,
        <johannes@sipsolutions.net>
CC:     <ath11k@lists.infradead.org>, <linux-wireless@vger.kernel.org>
References: <20221220043823.20382-1-quic_mpubbise@quicinc.com>
 <5DAEA8B2-2B44-4A91-9E57-12B6C6B6C1FC@holtmann.org>
 <2861463e-a097-7efe-bc75-f13c8faf9547@quicinc.com>
 <378a1d63b3752ace7384c44d6f5184753fa7795d.camel@gmail.com>
 <0b06dea9-d5be-1edc-62ca-576398d1bcd8@quicinc.com>
 <0e7644cbfa9e4ba0d534681166ca467ea1684719.camel@gmail.com>
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From:   Manikanta Pubbisetty <quic_mpubbise@quicinc.com>
In-Reply-To: <0e7644cbfa9e4ba0d534681166ca467ea1684719.camel@gmail.com>
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On 1/10/2023 10:35 PM, James Prestwood wrote:
> On Tue, 2023-01-10 at 10:49 +0530, Manikanta Pubbisetty wrote:
>> On 12/29/2022 2:52 AM, James Prestwood wrote:
>>> Hi Manikanta,
>>>> By the way, userspace itself selects the frequencies to scan, not
>>>> the
>>>> driver.
>>>>
>>>> If we see the split scan implementation in cfg80211, this is the
>>>> how
>>>> it
>>>> is implemented. If NL80211_SCAN_FLAG_COLOCATED_6GHZ is set, it
>>>> selects
>>>> all PSC channels and those non-PSC channels where RNR IE
>>>> information
>>>> is
>>>> found in the legacy scan results. If this flag is not set, all
>>>> channels
>>>> in 6 GHz are included in the scan freq list. It is upto userspace
>>>> to
>>>> decide what it wants.
>>>
>>>
>>> This isn't your problem, but it needs to be said:
>>>
>>> The nl80211 docs need and update to reflect this behavior (or
>>> remove
>>> the PSC logic). IMO this is really weird that the kernel selects
>>> PSC's
>>> based on the co-located flag. The docs don't describe this behavior
>>> and
>>> the flag's name is misleading (its not
>>> SCAN_FLAG_COLOCATED_AND_PSC_6GHZ) :)
>>>
>>
>> Sorry for the late reply, I was on vacation.
>>
>> What you said make sense. The existing flag should not add PSC
>> channels
>> according to the flag description.
>>
>> We can add another flag something like you pointed out
>> SCAN_FLAG_COLOCATED_AND_PSC_6GHZ and include PSC channels if this
>> flag
>> is set. What do you say?
> 
> I'm no authority here, just wanted to point this out. This is something
> that would need to be in mac80211 though, not just a specific driver.
> It would be up to the maintainers and would require changing the
> behavior of the existing flag, which then changes behavior in
> wpa_supplicant/hostapd. So its somewhat intrusive.
> 
> But personally I'd be for it. And just require userspace include PSC's
> like any other channels if they need those.
> 

Hi Johannes,

What is your opinion on the changes being proposed to the 6 GHz scan in 
cfg80211 that is being discussed in this thread?

Thanks,
Manikanta