[PATCH] wifi: ath12k: don't count a vdev restart as a started vdev

[Birk Skyum]

ath12k_mac_vdev_start_restart() increments ar->num_started_vdevs for a
restart as well as for a start. A restart is not paired with a stop, so
each one leaves the count one too high until the driver is restarted.
ath12k_mac_update_vif_chan() restarts every vdev that is up when its
channel context changes, for example when the AP changes the bandwidth
of the link.

Since commit 18ae7d0cdd76 ("wifi: ath12k: Avoid CPU busy-wait by
handling VDEV_STAT and BCN_STAT"), ath12k_wmi_fw_stats_process()
completes a WMI_REQUEST_VDEV_STAT request only after as many vdev stats
events as there are started vdevs. With the count too high that never
happens, so from then on every station statistics request waits the
full 3 seconds in ath12k_mac_get_fw_stats(), with the wiphy lock held,
and logs "time out while waiting for fw stats done".

On a Lenovo Yoga Slim 7x connected to an MLO AP, the timeouts start a
few seconds after the AP narrows its 5 GHz link from 160 to 80 MHz and
repeat every 3 seconds until the driver is reloaded. While they last,
channel switches take minutes to complete, transmits fail in bursts and
group rekeys end in a deauthentication.

Count only vdev starts, as ath11k does.

With this change the Yoga went through the AP's next switch of that
link, from channel 128 to channel 36 at 80 MHz, without a single
timeout, and the switch completed in under two seconds.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3

Fixes: d889913205cf ("wifi: ath12k: driver for Qualcomm Wi-Fi 7 devices")
Signed-off-by: Birk Skyum <birk.skyum at pm.me>
---
 drivers/net/wireless/ath/ath12k/mac.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath12k/mac.c b/drivers/net/wireless/ath/ath12k/mac.c
index 01f8c65..1b46723 100644
--- a/drivers/net/wireless/ath/ath12k/mac.c
+++ b/drivers/net/wireless/ath/ath12k/mac.c
@@ -11472,7 +11472,8 @@ ath12k_mac_vdev_start_restart(struct ath12k_link_vif *arvif,
 						   &arvif->reg_tpc_info);
 	}
 
-	ar->num_started_vdevs++;
+	if (!restart)
+		ar->num_started_vdevs++;
 	ath12k_dbg(ab, ATH12K_DBG_MAC,  "vdev %pM started, vdev_id %d\n",
 		   ahvif->vif->addr, arvif->vdev_id);
 
base-commit: cd026e68fdbf88b9cc522b76c7a9d92c9a41f709
-- 
2.53.0