From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     Felix Fietkau <nbd@nbd.name>, linux-wireless@vger.kernel.org
Subject: Re: [PATCH 1/6] mt76: use mac80211 txq scheduling
In-Reply-To: <111434f9-f04c-2fe2-c2b4-de757efc884c@nbd.name>
References: <20190316204242.73560-1-nbd@nbd.name> <87muluv4hd.fsf@toke.dk> <7b9a0a24-14b0-9b96-0010-ce9f96308ad0@nbd.name> <875zshviqg.fsf@toke.dk> <2cc1f1d4-f07e-faa0-ede7-95dd2917a64a@nbd.name> <87r2b5tb6a.fsf@toke.dk> <111434f9-f04c-2fe2-c2b4-de757efc884c@nbd.name>
Date:   Mon, 18 Mar 2019 23:14:28 +0100
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Felix Fietkau <nbd@nbd.name> writes:

> On 2019-03-17 22:59, Toke Høiland-Jørgensen wrote:
>> Felix Fietkau <nbd@nbd.name> writes:
>>> I've looked at ath9k (the only user at the moment), and it seems to call
>>> the function in that way already: at PS wake or tx status time if it has
>>> frames in its internal retry queue.
>>> While it does not match the current documented behavior for that
>>> function, it nicely fits ath9k's currently unfulfilled expectations ;)
>> 
>> Heh, fair point :)
> I noticed another issue: after the migration to the mac80211 txq
> scheduling code, ath9k does not handle stations going to powersave
> properly anymore. mac80211 keeps returning txqs for stations that have
> gone to sleep and ath9k will send out frames for them.

Ah, right. Never did have a good grip on the powersave code...

> We could deal with this in the driver and simply not return queues for
> stations in PS mode, or mac80211 could actively cancel them once a
> station enters PS mode. What do you prefer?

I think the cleanest would be if mac80211 handled it and just
un-scheduled stations when they go to sleep.

BTW, I was just thinking the other day about why the retry queue is kept
around when a station goes to sleep? Isn't the station usually sleeping
pretty long (>100 ms), where it might make more sense to drop things
rather than try again once i comes back?

-Toke