From d3fd2c95c1c13ec217d43ebef3c61cfa00a6cd37 Mon Sep 17 00:00:00 2001
From: Loic Poulain <loic.poulain@linaro.org>
Date: Mon, 25 Oct 2021 16:12:18 +0300
Subject: [PATCH] wcn36xx: Fix (QoS) null data frame bitrate/modulation
Git-commit: d3fd2c95c1c13ec217d43ebef3c61cfa00a6cd37
Patch-mainline: v5.16-rc1
References: git-fixes stable-5.14.19

We observe unexpected connection drops with some APs due to
non-acked mac80211 generated null data frames (keep-alive).
After debugging and capture, we noticed that null frames are
submitted at standard data bitrate and that the given APs are
in trouble with that.

After setting the null frame bitrate to control bitrate, all
null frames are acked as expected and connection is maintained.

Not sure if it's a requirement of the specification, but it seems
the right thing to do anyway, null frames are mostly used for control
purpose (power-saving, keep-alive...), and submitting them with
a slower/simpler bitrate/modulation is more robust.

Cc: stable@vger.kernel.org
Fixes: 512b191d9652 ("wcn36xx: Fix TX data path")
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1634560399-15290-1-git-send-email-loic.poulain@linaro.org
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/wireless/ath/wcn36xx/txrx.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/wireless/ath/wcn36xx/txrx.c b/drivers/net/wireless/ath/wcn36xx/txrx.c
index cab196bb38cd..e2d09d529146 100644
--- a/drivers/net/wireless/ath/wcn36xx/txrx.c
+++ b/drivers/net/wireless/ath/wcn36xx/txrx.c
@@ -429,6 +429,7 @@ static void wcn36xx_set_tx_data(struct wcn36xx_tx_bd *bd,
 	if (ieee80211_is_any_nullfunc(hdr->frame_control)) {
 		/* Don't use a regular queue for null packet (no ampdu) */
 		bd->queue_id = WCN36XX_TX_U_WQ_ID;
+		bd->bd_rate = WCN36XX_BD_RATE_CTRL;
 	}
 
 	if (bcast) {
-- 
2.26.2