mt76: MT7921K monitor mode not working

[sean.wang at mediatek.com]

From: Sean Wang <sean.wang at mediatek.com>

>> From: Sean Wang <sean.wang at mediatek.com>
>>
>> >> On Thursday, 2 December 2021 23:13:31 CET Lorenzo Bianconi wrote:
>> >> > IIRC you need to disable runtime-pm and deep-sleep to proper
>> >> > enable monitor
>> >> > mode:
>> >> >
>> >> > echo 0 > /sys/kernel/debug/ieee80211/phy<x>/mt76/runtime-pm
>> >> > echo 0 > /sys/kernel/debug/ieee80211/phy<x>/mt76/deep-sleep
>> >> >
>> >> > Can you please give it whirl?
>> >>
>> >> Jan gave me the card. I've set it to a rather busy channel (2.4GHz
>> >> channel 11), created a monitor interface, attached tcpdump and then
>> >> waited what happens. I didn't get anything and then I've tried to
>> >> set runtime-pm and deep- sleep to 0. This didn't change the
>> >> behavior for me at lot. I saw two packets and then it went silent again.
>> >>
>> >> I wanted to try the same on a different card (ath11k) in the same
>> >> system. But it crashed my complete system - so I had to recreate
>> >> the test setup. This time, I've set runtime-pm + deep-sleep to 0
>> >> before creating mon0. After doing this, it seemed to work.
>> >
>> >interesting, adding Sean to the loop here.
>> >It seems the fw is mainting a different state in this case.
>>
>> fw cannot receive any frame on monitor mode in deeply doze mode
>>
>> so it seemed to me we need a patch to explicitly disable pm runtime in driver when monitor interface is enabled until it is being disabled.
>
>ack, I agree, but I guess the point here is what is the difference (from the fw pov) if you disable runtime-pm/deep-sleep before/after the vif is added. I guess it is supposed to be the same, right?

yes, it is supposed to be the same.

>
>Regards,
>Lorenzo
>
>>
>> >
>> >@Sean: any pointers?
>> >
>> >Regards,
>> >Lorenzo
>> >
>> >>
>> >> Kind regards,
>> >>	Sven
>> >
>>
>