Subject: Re: [PATCH v3 2/2] mt76: mt7915: fix radar detector logic
To:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
References: <20210820203531.20706-1-greearb@candelatech.com>
 <20210820203531.20706-2-greearb@candelatech.com>
From:   Ben Greear <greearb@candelatech.com>
Organization: Candela Technologies
Message-ID: <950c52e2-8422-36f0-9024-55e45ef2672c@candelatech.com>
Date:   Wed, 10 Nov 2021 12:32:50 -0800
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On 8/20/21 1:35 PM, greearb@candelatech.com wrote:
> From: Ben Greear <greearb@candelatech.com>
> 
> Before this patch, if AP went from ch 100 to ch 36, the radar detector
> logic in the firmware was not being disabled.  This made the AP appear
> to be up, but no beacons were seen on air until module reload or
> reboot.
> 
> To reproduce this, I change hostapd.conf and restart hostapd.  Others
> on openwrt used their UI to make changes and problem was seen, but
> stil others changed channels in some other way and/or had some other
> difference and could *not* reproduce it.  So, something perhaps a
> bit subtle.
> 
> To fix the problem, stop depending on comparing dfs_state, store last
> freq/bandwidth to detect changes in that, and streamline code that
> checks to enable/disable radar detection.  And add in error checking
> and dev_dbg logic so one can see what is actually happening if need
> to debug this again.

Back when I was working on this, someone sent me an email or chat or something
about some other way to do this that was simpler and just relied on
mac80211 timers.  But, I cannot find that email for the life of me.

In case you are reading, please resend!  Evidently this 2/2 patch had
some regression for someone so it is not acceptable upstream in
current state...maybe the mac80211 option is best.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com