RE: [PATCH rtw-next v6 2/2] wifi: rtw88: support channel switch in AP mode

[Ping-Ke Shih]

Mehmet Fide <mehmet.fide@xxxxxxxxx> wrote:
> Hi Ping-Ke,
> 
> On 2026-10-19, Ping-Ke Shih wrote:
> > If you download beacon to firmware twice within a period of beacon_int,
> > a countdown in the air will not present, no? Like this
> [...]
> > The 4 is missing.
> 
> Yes, when a download runs late past the next TBTT. The absolute due
> time keeps the pace, one download per beacon interval on average, so
> the AP switches when its stations expect it; v5 queued relative to
> the previous download and drifted 10 ms per beacon on USB. The price
> of a download that late is one stale beacon and one count never sent.
> A station takes its switch time from the counts it sees; at worst one
> whose first count is the stale one switches one interval late.
> 
> Forced on an RTL8821CU with a 90 ms delay on every second download: a
> sniffer saw 9, 8, 8, 6, 4, 4, 2, 2 for count 10, the AP finished on
> time, and a Windows station followed ten such switches (counts 10 and
> 50) without a re-association. Without the delay it happened once in
> nine switches.
> 
> If you would rather not have it: timing the downloads from the TSF,
> 10 ms after each TBTT, leaves nearly a whole interval before a beacon
> goes out without the download. I tried that briefly on the 8821CU;
> with a 60 ms delay every count stays on the air. Which do you prefer?

It'd be better to see every count stays on the air. Will you implement
to handle TBTT events? Can you share a draft first or a separate patch
(e.g. patch 3/3 to improve missing count)? 

Ping-Ke