mac80211: ath: improve ath10k "failed to flush transmit queue" errors

Currently, in busy environments, ath10k logs "failed to flush transmit
queue" errors and have a spiking CPU usage, making the wireless barely
usable.
With this patch, taken from https://patchwork.kernel.org/project/linux-wireless/patch/20250806070005.1429-1-hujy652@gmail.com/
this does not occur in normal operation and the wifi is much more stable

Supersedes #19427
Ref: https://github.com/openwrt/openwrt/issues/15929#issuecomment-2227391307
Ref: https://github.com/openwrt/openwrt/issues/14965

Signed-off-by: Florian Maurer <f.maurer@outlook.de>
Link: https://github.com/openwrt/openwrt/pull/19529
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

diff --git a/package/kernel/mac80211/patches/ath10k/991-ath10k-support-flush_sta-method.patch b/package/kernel/mac80211/patches/ath10k/991-ath10k-support-flush_sta-method.patch
new file mode 100644 (file)
index 0000000..a0f6eed
--- /dev/null
+++ b/package/kernel/mac80211/patches/ath10k/991-ath10k-support-flush_sta-method.patch
@@ -0,0 +1,70 @@
+From: Zhi-Jun You <hujy652@gmail.com>
+Date: Wed,  6 Aug 2025 15:00:05 +0800
+Subject: [RFC PATCH] wifi: ath10k: support flush_sta method
+
+
+When a STA is marked as no longer authorized, if the driver doesn't
+implement flush_sta(), mac80211 calls ieee80211_flush_queues() to
+flush hardware queues to avoid sending unencrypted frames.
+
+This has became a problem for ath10k because ieee80211_flush_queues()
+will stop all traffic and call ath10k_flush, which waits until the
+whole HW queue is empty. In a busy environment this will trigger a
+timeout warning and stalls other STAs.
+
+Fix this by implementing flush_sta method using WMI command to flush
+frames of a specific STA.
+Flushed frames will be marked as discard in tx complete indication.
+
+ops->flush_sta will be set to NULL if htt.disable_tx_comp is set to
+true.
+
+Tested-on: QCA9984 hw1.0 PCI 10.4-3.9.0.2-00157
+
+Signed-off-by: Zhi-Jun You <hujy652@gmail.com>
+Tested-by: Florian Maurer <maurer@fh-aachen.de>
+---
+ drivers/net/wireless/ath/ath10k/mac.c | 18 ++++++++++++++++++
+ 1 file changed, 18 insertions(+)
+
+--- a/drivers/net/wireless/ath/ath10k/mac.c
++++ b/drivers/net/wireless/ath/ath10k/mac.c
+@@ -8166,6 +8166,20 @@ static void ath10k_flush(struct ieee8021
+       mutex_unlock(&ar->conf_mutex);
+ }
+ 
++static void ath10k_mac_op_flush_sta(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
++                           struct ieee80211_sta *sta)
++{
++      struct ath10k_vif *arvif = (void *)vif->drv_priv;
++      struct ath10k *ar = hw->priv;
++      u32 bitmap = 0xFFFFFFFF;
++      int ret = 0;
++
++      ret = ath10k_wmi_peer_flush(ar, arvif->vdev_id, sta->addr, bitmap);
++      if (ret)
++              ath10k_warn(ar, "failed to flush sta (sta %pM)\n",
++                          sta->addr);
++}
++
+ /* TODO: Implement this function properly
+  * For now it is needed to reply to Probe Requests in IBSS mode.
+  * Probably we need this information from FW.
+@@ -9513,6 +9527,7 @@ static const struct ieee80211_ops ath10k
+       .set_rts_threshold              = ath10k_set_rts_threshold,
+       .set_frag_threshold             = ath10k_mac_op_set_frag_threshold,
+       .flush                          = ath10k_flush,
++      .flush_sta                      = ath10k_mac_op_flush_sta,
+       .tx_last_beacon                 = ath10k_tx_last_beacon,
+       .set_antenna                    = ath10k_set_antenna,
+       .get_antenna                    = ath10k_get_antenna,
+@@ -10334,6 +10349,9 @@ int ath10k_mac_register(struct ath10k *a
+       if (!ar->hw_params.hw_ops->set_coverage_class)
+               ar->ops->set_coverage_class = NULL;
+ 
++      if (ar->htt.disable_tx_comp)
++              ar->ops->flush_sta = NULL;
++
+       ret = ath_regd_init(&ar->ath_common.regulatory, ar->hw->wiphy,
+                           ath10k_reg_notifier);
+       if (ret) {