ath10k: disable wake_tx_queue for older devices

Ideally wake_tx_queue should be used regardless as
it is a requirement for reducing bufferbloat and
implementing airtime fairness in the future.

However some setups (typically low-end platforms
hosting QCA988X) suffer performance regressions
with the current wake_tx_queue implementation.
Therefore disable it unless it is really
beneficial with current codebase (which is when
firmware supports smart pull-push tx scheduling).
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/core.h

@@ -676,6 +676,7 @@ struct ath10k_fw_components {
 struct ath10k {
 	struct ath_common ath_common;
 	struct ieee80211_hw *hw;
+	struct ieee80211_ops *ops;
 	struct device *dev;
 	u8 mac_addr[ETH_ALEN];
 

drivers/net/wireless/ath/ath10k/mac.c

@@ -7506,21 +7506,32 @@ static const struct ieee80211_channel ath10k_5ghz_channels[] = {
 struct ath10k *ath10k_mac_create(size_t priv_size)
 {
 	struct ieee80211_hw *hw;
+	struct ieee80211_ops *ops;
 	struct ath10k *ar;
 
-	hw = ieee80211_alloc_hw(sizeof(struct ath10k) + priv_size, &ath10k_ops);
-	if (!hw)
+	ops = kmemdup(&ath10k_ops, sizeof(ath10k_ops), GFP_KERNEL);
+	if (!ops)
 		return NULL;
 
+	hw = ieee80211_alloc_hw(sizeof(struct ath10k) + priv_size, ops);
+	if (!hw) {
+		kfree(ops);
+		return NULL;
+	}
+
 	ar = hw->priv;
 	ar->hw = hw;
+	ar->ops = ops;
 
 	return ar;
 }
 
 void ath10k_mac_destroy(struct ath10k *ar)
 {
+	struct ieee80211_ops *ops = ar->ops;
+
 	ieee80211_free_hw(ar->hw);
+	kfree(ops);
 }
 
 static const struct ieee80211_iface_limit ath10k_if_limits[] = {
@@ -7954,6 +7965,15 @@ int ath10k_mac_register(struct ath10k *ar)
 			ath10k_warn(ar, "failed to initialise DFS pattern detector\n");
 	}
 
+	/* Current wake_tx_queue implementation imposes a significant
+	 * performance penalty in some setups. The tx scheduling code needs
+	 * more work anyway so disable the wake_tx_queue unless firmware
+	 * supports the pull-push mechanism.
+	 */
+	if (!test_bit(ATH10K_FW_FEATURE_PEER_FLOW_CONTROL,
+		      ar->running_fw->fw_file.fw_features))
+		ar->ops->wake_tx_queue = NULL;
+
 	ret = ath_regd_init(&ar->ath_common.regulatory, ar->hw->wiphy,
 			    ath10k_reg_notifier);
 	if (ret) {