* [PATCH v8 1/2] wifi: ath12k: remove skb parameter from get_ring_selector
2026-10-21 6:09 [PATCH v8 0/2] wifi: ath12k: implement TX flow control Jose Ignacio Tornos Martinez
@ 2026-10-21 6:09 ` Jose Ignacio Tornos Martinez
2026-10-21 6:09 ` [PATCH v8 2/2] wifi: ath12k: implement custom wake_tx_queue with flow control Jose Ignacio Tornos Martinez
1 sibling, 0 replies; 3+ messages in thread
From: Jose Ignacio Tornos Martinez @ 2026-10-21 6:09 UTC (permalink / raw)
To: jjohnson
Cc: ath11k, ath12k, linux-wireless, linux-kernel,
Jose Ignacio Tornos Martinez
Change the get_ring_selector hw_ops callback signature from
get_ring_selector(struct sk_buff *skb) to get_ring_selector(u8 ac),
removing the dependency on the skb.
All ath12k get_ring_selector implementations fall into two categories:
- smp_processor_id(): ignores the skb entirely
- skb_get_queue_mapping(): only reads the AC value from the skb
Since the AC is the only information extracted from the skb, pass it
directly as a u8 parameter instead. Callers in the dp_tx path now
pass skb_get_queue_mapping(skb), which preserves the exact same
behavior.
This change enables a subsequent patch to call get_ring_selector()
from wake_tx_queue using txq->ac, without needing access to the skb.
mac80211 guarantees that skb_get_queue_mapping(skb) == txq->ac
for any skb dequeued from a given txq, since both values are
derived from the same skb->priority through the same AC mapping.
No functional change.
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3
Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
---
v8: Split ath11k and ath12k into separate series to avoid conflict
with Julius's airtime queue limits series (ath11k only) and help to
unblock both
No code changes from v7
v7: https://lore.kernel.org/all/20260917064825.12747-3-jtornosm@redhat.com/
drivers/net/wireless/ath/ath12k/hw.h | 2 +-
drivers/net/wireless/ath/ath12k/wifi7/dp_tx.c | 2 +-
drivers/net/wireless/ath/ath12k/wifi7/hw.c | 6 +++---
3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/net/wireless/ath/ath12k/hw.h b/drivers/net/wireless/ath/ath12k/hw.h
index 86fb8b719613..65caa7a2349f 100644
--- a/drivers/net/wireless/ath/ath12k/hw.h
+++ b/drivers/net/wireless/ath/ath12k/hw.h
@@ -243,7 +243,7 @@ struct ath12k_hw_ops {
int (*mac_id_to_pdev_id)(const struct ath12k_hw_params *hw, int mac_id);
int (*mac_id_to_srng_id)(const struct ath12k_hw_params *hw, int mac_id);
int (*rxdma_ring_sel_config)(struct ath12k_base *ab);
- u8 (*get_ring_selector)(struct sk_buff *skb);
+ u8 (*get_ring_selector)(u8 ac);
bool (*dp_srng_is_tx_comp_ring)(int ring_num);
bool (*is_frame_link_agnostic)(struct ath12k_link_vif *arvif,
struct ieee80211_mgmt *mgmt);
diff --git a/drivers/net/wireless/ath/ath12k/wifi7/dp_tx.c b/drivers/net/wireless/ath/ath12k/wifi7/dp_tx.c
index d2749de44553..74359e8eea47 100644
--- a/drivers/net/wireless/ath/ath12k/wifi7/dp_tx.c
+++ b/drivers/net/wireless/ath/ath12k/wifi7/dp_tx.c
@@ -111,7 +111,7 @@ int ath12k_wifi7_dp_tx(struct ath12k_pdev_dp *dp_pdev, struct ath12k_link_vif *a
* If all rings are full, we drop the packet.
* TODO: Add throttling logic when all rings are full
*/
- ring_selector = dp->hw_params->hw_ops->get_ring_selector(skb);
+ ring_selector = dp->hw_params->hw_ops->get_ring_selector(skb_get_queue_mapping(skb));
tcl_ring_sel:
tcl_ring_retry = false;
diff --git a/drivers/net/wireless/ath/ath12k/wifi7/hw.c b/drivers/net/wireless/ath/ath12k/wifi7/hw.c
index d9fdd2fc8298..7436cf70925a 100644
--- a/drivers/net/wireless/ath/ath12k/wifi7/hw.c
+++ b/drivers/net/wireless/ath/ath12k/wifi7/hw.c
@@ -49,7 +49,7 @@ ath12k_wifi7_hw_mac_id_to_srng_id_qcn9274(const struct ath12k_hw_params *hw,
return 0;
}
-static u8 ath12k_wifi7_hw_get_ring_selector_qcn9274(struct sk_buff *skb)
+static u8 ath12k_wifi7_hw_get_ring_selector_qcn9274(u8 ac)
{
return smp_processor_id();
}
@@ -83,9 +83,9 @@ ath12k_wifi7_hw_mac_id_to_srng_id_wcn7850(const struct ath12k_hw_params *hw,
return mac_id;
}
-static u8 ath12k_wifi7_hw_get_ring_selector_wcn7850(struct sk_buff *skb)
+static u8 ath12k_wifi7_hw_get_ring_selector_wcn7850(u8 ac)
{
- return skb_get_queue_mapping(skb);
+ return ac;
}
static bool ath12k_wifi7_dp_srng_is_comp_ring_wcn7850(int ring_num)
--
2.54.0
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH v8 2/2] wifi: ath12k: implement custom wake_tx_queue with flow control
2026-10-21 6:09 [PATCH v8 0/2] wifi: ath12k: implement TX flow control Jose Ignacio Tornos Martinez
2026-10-21 6:09 ` [PATCH v8 1/2] wifi: ath12k: remove skb parameter from get_ring_selector Jose Ignacio Tornos Martinez
@ 2026-10-21 6:09 ` Jose Ignacio Tornos Martinez
1 sibling, 0 replies; 3+ messages in thread
From: Jose Ignacio Tornos Martinez @ 2026-10-21 6:09 UTC (permalink / raw)
To: jjohnson
Cc: ath11k, ath12k, linux-wireless, linux-kernel,
Jose Ignacio Tornos Martinez
Under heavy traffic, ath12k can hang and experiences -ENOMEM errors
("failed to transmit frame -12") when the hardware TCL ring fills up.
This issue is more commonly observed in VMs with PCIe passthrough but
also occurs on bare metal systems.
Implement a custom wake_tx_queue operation that:
1. Checks hardware ring space before dequeuing packets from mac80211
2. Uses per-ring locking (wake_tx_lock with spin_lock_bh) to serialize
concurrent wake_tx_queue calls targeting the same ring and to ensure
bottom halves are disabled as required by ieee80211_tx_dequeue()
3. Syncs with hardware state to get accurate free slot count
4. Resolves the target TCL ring once using get_ring_selector(txq->ac),
which selects the ring based on the access category
5. Returns early during firmware crash in the same way as other
tx paths
This approach follows the pattern used in the iwlwifi driver, adapted
for ath12k's hardware ring architecture.
This prevents hangs, eliminates -ENOMEM errors, and improves throughput
by optimizing resource usage and preventing unnecessary packet drops.
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3
Signed-off-by: Jose Ignacio Tornos Martinez <jtornosm@redhat.com>
---
v8: Split ath11k and ath12k into separate series to avoid conflict
with Julius's airtime queue limits series (ath11k only) and help to
unblock both
No code changes from v7
v7: https://lore.kernel.org/all/20260917064825.12747-5-jtornosm@redhat.com/
drivers/net/wireless/ath/ath12k/dp.c | 1 +
drivers/net/wireless/ath/ath12k/dp.h | 2 +
drivers/net/wireless/ath/ath12k/hal.c | 1 +
drivers/net/wireless/ath/ath12k/wifi7/hw.c | 69 +++++++++++++++++++++-
4 files changed, 72 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wireless/ath/ath12k/dp.c b/drivers/net/wireless/ath/ath12k/dp.c
index f9b37d75956d..e62fa416b992 100644
--- a/drivers/net/wireless/ath/ath12k/dp.c
+++ b/drivers/net/wireless/ath/ath12k/dp.c
@@ -1537,6 +1537,7 @@ static int ath12k_dp_setup(struct ath12k_base *ab)
}
for (i = 0; i < ab->hw_params->max_tx_ring; i++) {
+ spin_lock_init(&dp->tx_ring[i].wake_tx_lock);
dp->tx_ring[i].tcl_data_ring_id = i;
dp->tx_ring[i].tx_status_head = 0;
diff --git a/drivers/net/wireless/ath/ath12k/dp.h b/drivers/net/wireless/ath/ath12k/dp.h
index bef0f2ba0560..4bf8a8a6d76c 100644
--- a/drivers/net/wireless/ath/ath12k/dp.h
+++ b/drivers/net/wireless/ath/ath12k/dp.h
@@ -58,6 +58,8 @@ struct dp_tx_ring {
u8 tcl_data_ring_id;
struct dp_srng tcl_data_ring;
struct dp_srng tcl_comp_ring;
+ /* Serializes wake_tx_queue operations for this ring */
+ spinlock_t wake_tx_lock;
struct hal_wbm_completion_ring_tx *tx_status;
int tx_status_head;
int tx_status_tail;
diff --git a/drivers/net/wireless/ath/ath12k/hal.c b/drivers/net/wireless/ath/ath12k/hal.c
index c0c3d2f047ef..fbe4dc41e34b 100644
--- a/drivers/net/wireless/ath/ath12k/hal.c
+++ b/drivers/net/wireless/ath/ath12k/hal.c
@@ -390,6 +390,7 @@ int ath12k_hal_srng_src_num_free(struct ath12k_base *ab, struct hal_srng *srng,
else
return ((srng->ring_size - hp + tp) / srng->entry_size) - 1;
}
+EXPORT_SYMBOL(ath12k_hal_srng_src_num_free);
void *ath12k_hal_srng_src_next_peek(struct ath12k_base *ab,
struct hal_srng *srng)
diff --git a/drivers/net/wireless/ath/ath12k/wifi7/hw.c b/drivers/net/wireless/ath/ath12k/wifi7/hw.c
index 678c512a2199..7bfeb9397465 100644
--- a/drivers/net/wireless/ath/ath12k/wifi7/hw.c
+++ b/drivers/net/wireless/ath/ath12k/wifi7/hw.c
@@ -1160,9 +1160,76 @@ static void ath12k_wifi7_mac_op_tx(struct ieee80211_hw *hw,
}
}
+static void ath12k_wifi7_mac_op_wake_tx_queue(struct ieee80211_hw *hw,
+ struct ieee80211_txq *txq)
+{
+ struct ath12k_vif *ahvif = ath12k_vif_to_ahvif(txq->vif);
+ struct ieee80211_tx_control control = {
+ .sta = txq->sta,
+ };
+ struct ieee80211_vif *vif = txq->vif;
+ struct ath12k_link_vif *arvif;
+ struct dp_tx_ring *tx_ring;
+ struct hal_srng *tcl_ring;
+ struct ath12k_sta *ahsta;
+ struct ath12k_dp *dp;
+ struct sk_buff *skb;
+ struct ath12k *ar;
+ u8 ring_selector;
+ int num_free;
+ u8 ring_id;
+ u8 link_id;
+
+ if (ieee80211_vif_is_mld(vif) && txq->sta) {
+ ahsta = ath12k_sta_to_ahsta(txq->sta);
+ link_id = ahsta->assoc_link_id;
+ } else {
+ link_id = ahvif->deflink.link_id;
+ }
+
+ rcu_read_lock();
+
+ arvif = rcu_dereference(ahvif->link[link_id]);
+ if (!arvif || !arvif->ar) {
+ rcu_read_unlock();
+ return;
+ }
+
+ ar = arvif->ar;
+ dp = ar->ab->dp;
+
+ ring_selector = dp->hw_params->hw_ops->get_ring_selector(txq->ac);
+ ring_id = ring_selector % dp->hw_params->max_tx_ring;
+ tx_ring = &dp->tx_ring[ring_id];
+ tcl_ring = &dp->hal->srng_list[tx_ring->tcl_data_ring.ring_id];
+
+ while (1) {
+ if (unlikely(test_bit(ATH12K_FLAG_CRASH_FLUSH,
+ &ar->ab->dev_flags)))
+ break;
+
+ guard(spinlock_bh)(&tx_ring->wake_tx_lock);
+
+ spin_lock_bh(&tcl_ring->lock);
+ num_free = ath12k_hal_srng_src_num_free(ar->ab, tcl_ring, true);
+ spin_unlock_bh(&tcl_ring->lock);
+
+ if (num_free == 0)
+ break;
+
+ skb = ieee80211_tx_dequeue(hw, txq);
+ if (!skb)
+ break;
+
+ ath12k_wifi7_mac_op_tx(hw, &control, skb);
+ }
+
+ rcu_read_unlock();
+}
+
static const struct ieee80211_ops ath12k_ops_wifi7 = {
.tx = ath12k_wifi7_mac_op_tx,
- .wake_tx_queue = ieee80211_handle_wake_tx_queue,
+ .wake_tx_queue = ath12k_wifi7_mac_op_wake_tx_queue,
.start = ath12k_mac_op_start,
.stop = ath12k_mac_op_stop,
.reconfig_complete = ath12k_mac_op_reconfig_complete,
--
2.54.0
^ permalink raw reply [flat|nested] 3+ messages in thread