[PATCH rtw-next v2 2/2] wifi: rtw88: sdio: limit the high queue to DTIM delivery

[Luka Gejak <luka.gejak@linux.dev>]

In AP mode every broadcast and multicast (bmc) frame is sent through the
high queue, which the hardware only drains after a DTIM beacon. Only a
few frames leave per DTIM, so steady multicast traffic builds a backlog
that holds the TX pages the other queues need. Unicast traffic then
stalls for seconds and clients can no longer renew their DHCP lease.

USB had the same problem and was fixed by commit c710c7c2e038 ("wifi:
rtw88: usb: route bmc frames via the high queue only for DTIM delivery")
and the two commits that followed it. Use the same rule for SDIO. A bmc
frame goes to the high queue only when mac80211 asks for DTIM delivery
because a station is dozing, the frame is ARP, EAPOL or DHCP, and the
budget allows it. All other bmc frames go out on their access category
queue.

Tested on RTL8723BS with an ath9k client.

Signed-off-by: Luka Gejak <luka.gejak@linux.dev>
---
 drivers/net/wireless/realtek/rtw88/sdio.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtw88/sdio.c b/drivers/net/wireless/realtek/rtw88/sdio.c
index dc2fd0f8f9ff..83e9b301ae9b 100644
--- a/drivers/net/wireless/realtek/rtw88/sdio.c
+++ b/drivers/net/wireless/realtek/rtw88/sdio.c
@@ -1308,6 +1308,9 @@ static int rtw_sdio_tx_write(struct rtw_dev *rtwdev,
 	u16 q_map = skb_get_queue_mapping(skb);
 	struct rtw_sdio_tx_data *tx_data;
 
+	if (queue == RTW_TX_QUEUE_HI0 && !rtw_tx_bmc_use_hiq(rtwdev, skb))
+		queue = rtw_tx_ac_to_hwq(q_map);
+
 	rtw_sdio_tx_skb_prepare(rtwdev, pkt_info, skb, queue);
 
 	tx_data = rtw_sdio_get_tx_data(skb);
-- 
2.53.0