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Message-ID: <0e7644cbfa9e4ba0d534681166ca467ea1684719.camel@gmail.com>
Subject: Re: [PATCH] wifi: ath11k: Optimize 6 GHz scan time
From:   James Prestwood <prestwoj@gmail.com>
To:     Manikanta Pubbisetty <quic_mpubbise@quicinc.com>,
        Marcel Holtmann <marcel@holtmann.org>
Cc:     ath11k@lists.infradead.org, linux-wireless@vger.kernel.org
Date:   Tue, 10 Jan 2023 09:05:30 -0800
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         <5DAEA8B2-2B44-4A91-9E57-12B6C6B6C1FC@holtmann.org>
         <2861463e-a097-7efe-bc75-f13c8faf9547@quicinc.com>
         <378a1d63b3752ace7384c44d6f5184753fa7795d.camel@gmail.com>
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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.

Thanks,
James