[PATCH rtw-next] wifi: rtw88: usb: send broadcast/multicast via the AC queues

[Mehmet Fide]

From: Mehmet Fide <mehmet.fide@xxxxxxxxxxxxxxxxxx>

In AP mode every broadcast and multicast data frame is routed to
TX_DESC_QSEL_HIGH, the after-DTIM queue. The firmware drains that
queue at beacon pace, roughly a dozen frames per second, while a
single associated client's mDNS/SSDP chatter alone exceeds that.
The excess accumulates inside the chip until the shared TX page
pool is exhausted; measured on RTL8822BU, 14 of 1803 pages were
left. From that point every host-sourced frame queues behind the
backlog: authentication responses reach the air seconds after the
client has given up, so no station can associate anymore, and the
beacon reserved-page download fails the BCN_VALID poll ("error
beacon valid") because it needs pages from the same exhausted pool.
The AP keeps beaconing throughout, so from the outside this looks
like a silent receive stall, and only a reboot recovers.

On USB the HIGH, MGMT, BEACON and H2C queues additionally share one
bulk-out endpoint, so the jam also head-of-line blocks firmware
commands.

Route broadcast/multicast data through the regular AC queues
instead. They then leave at line rate and the page pool never
fills. The trade-off is that stations in power save may miss
multicast that the after-DTIM queue would have buffered for them;
at the chatter rates that trigger the jam those frames were being
dropped anyway.

On a bench AP (RTL8822BU, USB2, 20 MHz, WPA2, hostapd, a Windows
client driven through disconnect/reconnect cycles): reconnects fail
0/5 before this change and pass 5/5 with it, with the page pool
staying healthy and no beacon errors logged.

Signed-off-by: Mehmet Fide <mehmet.fide@xxxxxxxxxxxxxxxxxx>
---
 drivers/net/wireless/realtek/rtw88/usb.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/usb.c b/drivers/net/wireless/realtek/rtw88/usb.c
index 64e1c3420..f528fe0f2 100644
--- a/drivers/net/wireless/realtek/rtw88/usb.c
+++ b/drivers/net/wireless/realtek/rtw88/usb.c
@@ -565,9 +565,6 @@ static u8 rtw_usb_tx_queue_mapping_to_qsel(struct sk_buff *skb)
 
 	if (unlikely(ieee80211_is_mgmt(fc) || ieee80211_is_ctl(fc)))
 		qsel = TX_DESC_QSEL_MGMT;
-	else if (is_broadcast_ether_addr(hdr->addr1) ||
-		 is_multicast_ether_addr(hdr->addr1))
-		qsel = TX_DESC_QSEL_HIGH;
 	else if (skb_get_queue_mapping(skb) <= IEEE80211_AC_BK)
 		qsel = skb->priority;
 	else
-- 
2.54.0