Date:   Mon, 18 Mar 2019 10:50:15 +0100
From:   Stanislaw Gruszka <sgruszka@redhat.com>
To:     Felix Fietkau <nbd@nbd.name>
Cc:     linux-wireless@vger.kernel.org,
        Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Subject: Re: [PATCH 08/11] mt76x02u: implement pre TBTT work for USB
Message-ID: <20190318095014.GA3323@redhat.com>
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On Sat, Mar 16, 2019 at 08:44:21PM +0100, Felix Fietkau wrote:
> On 2019-03-04 10:48, Stanislaw Gruszka wrote:
> > Program beacons data and PS buffered frames on TBTT work for USB.
> > We do not have MT_TXQ_PSD queue available via USB endpoints. The way
> > we can send PS broadcast frames in timely manner before PS stations go
> > sleep again is program them in beacon data area. Hardware do not modify
> > those frames since TXWI is properly configured. mt76x02_mac_set_beacon()
> > already handle this and free no longer used frames.
> > 
> > Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
> I think it's a nice idea, but there is one problem with that approach:
> beacon slots only have 1024 bytes for TXWI + data.
> I think to support this properly, you probably need to adjust beacon
> offsets for USB dynamically and limit the number of frames to what you
> can fit in SRAM.
That would be good since we could sent more buffered frames (ARP frames
are small), but for now I would prefer simpler solution to enable 
AP support for USB: increase slot size to 1600 and make only 5 slots
available.

I assume we can not increase beacon SRAM area to more than 8kB.

Stanislaw