wifi: ath11k: skip status ring entry processing

If STATUS_BUFFER_DONE is not set for a monitor status ring entry,
we don't process the status ring until STATUS_BUFFER_DONE set
for that status ring entry.

During LMAC reset it may happen that hardware will not write
STATUS_BUFFER_DONE tlv in status buffer, in that case we end up
waiting for STATUS_BUFFER_DONE leading to backpressure on monitor
status ring.

To fix the issue, when HP(Head Pointer) + 1 entry is peeked and if DMA
is not done and if HP + 2 entry's DMA done is set,
replenish HP + 1 entry and start processing in next interrupt.
If HP + 2 entry's DMA done is not set, poll onto HP + 1 entry DMA
done to be set.

Also, during monitor attach HP points to the end of the ring and
TP(Tail Pointer) points to the start of the ring.
Using ath11k_hal_srng_src_peek() may result in processing invalid buffer
for the very first interrupt. Since, HW starts writing buffer from TP.

To avoid this issue call ath11k_hal_srng_src_next_peek() instead of
calling ath11k_hal_srng_src_peek().

Tested-on: IPQ5018 hw1.0 AHB WLAN.HK.2.6.0.1-00861-QCAHKSWPL_SILICONZ-1

Signed-off-by: Venkateswara Naralasetty <quic_vnaralas@quicinc.com>
Co-developed-by: Tamizh Chelvam Raja <quic_tamizhr@quicinc.com>
Signed-off-by: Tamizh Chelvam Raja <quic_tamizhr@quicinc.com>

drivers/net/wireless/ath/ath11k/dp_rx.c

@@ -2960,6 +2960,46 @@ ath11k_dp_rx_mon_update_status_buf_state(struct ath11k_mon_data *pmon,
 	}
 }
 
+enum dp_mon_status_buf_state
+ath11k_dp_rx_mon_handle_status_buf_done(struct ath11k_base *ab, struct hal_srng *srng,
+					struct dp_rxdma_ring *rx_ring)
+{
+	void *status_desc;
+	struct sk_buff *skb;
+	struct ath11k_skb_rxcb *rxcb;
+	struct hal_tlv_hdr *tlv;
+	dma_addr_t paddr;
+	u32 cookie;
+	int buf_id;
+	u8 rbm;
+
+	status_desc = ath11k_hal_srng_src_next_peek(ab, srng);
+	if (!status_desc)
+		return DP_MON_STATUS_NO_DMA;
+
+	ath11k_hal_rx_buf_addr_info_get(status_desc, &paddr, &cookie, &rbm);
+
+	buf_id = FIELD_GET(DP_RXDMA_BUF_COOKIE_BUF_ID, cookie);
+
+	spin_lock_bh(&rx_ring->idr_lock);
+	skb = idr_find(&rx_ring->bufs_idr, buf_id);
+	spin_unlock_bh(&rx_ring->idr_lock);
+
+	if (!skb)
+		return DP_MON_STATUS_NO_DMA;
+
+	rxcb = ATH11K_SKB_RXCB(skb);
+	dma_sync_single_for_cpu(ab->dev, rxcb->paddr,
+				skb->len + skb_tailroom(skb),
+				DMA_FROM_DEVICE);
+
+	tlv = (struct hal_tlv_hdr *)skb->data;
+	if (FIELD_GET(HAL_TLV_HDR_TAG, tlv->tl) != HAL_RX_STATUS_BUFFER_DONE)
+		return DP_MON_STATUS_NO_DMA;
+
+	return DP_MON_STATUS_REPLINISH;
+}
+
 static int ath11k_dp_rx_reap_mon_status_ring(struct ath11k_base *ab, int mac_id,
 					     int *budget, struct sk_buff_head *skb_list)
 {
@@ -2973,6 +3013,7 @@ static int ath11k_dp_rx_reap_mon_status_ring(struct ath11k_base *ab, int mac_id,
 	struct sk_buff *skb;
 	struct ath11k_skb_rxcb *rxcb;
 	struct hal_tlv_hdr *tlv;
+	enum dp_mon_status_buf_state reap_status;
 	u32 cookie;
 	int buf_id, srng_id;
 	dma_addr_t paddr;
@@ -2992,8 +3033,7 @@ static int ath11k_dp_rx_reap_mon_status_ring(struct ath11k_base *ab, int mac_id,
 	ath11k_hal_srng_access_begin(ab, srng);
 	while (*budget) {
 		*budget -= 1;
-		rx_mon_status_desc =
-			ath11k_hal_srng_src_peek(ab, srng);
+		rx_mon_status_desc = ath11k_hal_srng_src_peek(ab, srng);
 		if (!rx_mon_status_desc) {
 			pmon->buf_state = DP_MON_STATUS_REPLINISH;
 			break;
@@ -3024,18 +3064,43 @@ static int ath11k_dp_rx_reap_mon_status_ring(struct ath11k_base *ab, int mac_id,
 			tlv = (struct hal_tlv_hdr *)skb->data;
 			if (FIELD_GET(HAL_TLV_HDR_TAG, tlv->tl) !=
 					HAL_RX_STATUS_BUFFER_DONE) {
-				ath11k_warn(ab, "mon status DONE not set %lx, buf_id %d\n",
-					    FIELD_GET(HAL_TLV_HDR_TAG,
-						      tlv->tl), buf_id);
-				/* If done status is missing, hold onto status
-				 * ring until status is done for this status
-				 * ring buffer.
-				 * Keep HP in mon_status_ring unchanged,
-				 * and break from here.
-				 * Check status for same buffer for next time
+				/* RxDMA status done bit might not be set even
+				 * though tp is moved by HW.
 				 */
-				pmon->buf_state = DP_MON_STATUS_NO_DMA;
-				break;
+
+				/* If done status is missing:
+				 * 1. As per MAC team's suggestion,
+				 *    when HP + 1 entry is peeked and if DMA
+				 *    is not done and if HP + 2 entry's DMA done
+				 *    is set. skip HP + 1 entry and
+				 *    start processing in next interrupt.
+				 * 2. If HP + 2 entry's DMA done is not set,
+				 *    poll onto HP + 1 entry DMA done to be set.
+				 *    Check status for same buffer for next time
+				 *    dp_rx_mon_status_srng_process
+				 */
+
+				reap_status = ath11k_dp_rx_mon_handle_status_buf_done(ab, srng,
+										      rx_ring);
+				if (reap_status == DP_MON_STATUS_NO_DMA) {
+					continue;
+				} else if (reap_status == DP_MON_STATUS_REPLINISH) {
+					ath11k_warn(ab, "mon status DONE not set %lx, buf_id %d\n",
+						    FIELD_GET(HAL_TLV_HDR_TAG, tlv->tl),
+						    buf_id);
+
+					spin_lock_bh(&rx_ring->idr_lock);
+					idr_remove(&rx_ring->bufs_idr, buf_id);
+					spin_unlock_bh(&rx_ring->idr_lock);
+
+					dma_unmap_single(ab->dev, rxcb->paddr,
+							 skb->len + skb_tailroom(skb),
+							 DMA_FROM_DEVICE);
+
+					dev_kfree_skb_any(skb);
+					pmon->buf_state = DP_MON_STATUS_REPLINISH;
+					goto move_next;
+				}
 			}
 
 			spin_lock_bh(&rx_ring->idr_lock);

drivers/net/wireless/ath/ath11k/hal.c

@@ -783,6 +783,20 @@ u32 *ath11k_hal_srng_src_get_next_reaped(struct ath11k_base *ab,
 	return desc;
 }
 
+u32 *ath11k_hal_srng_src_next_peek(struct ath11k_base *ab, struct hal_srng *srng)
+{
+	u32 next_hp;
+
+	lockdep_assert_held(&srng->lock);
+
+	next_hp = (srng->u.src_ring.hp + srng->entry_size) % srng->ring_size;
+
+	if (next_hp != srng->u.src_ring.cached_tp)
+		return srng->ring_base_vaddr + next_hp;
+
+	return NULL;
+}
+
 u32 *ath11k_hal_srng_src_peek(struct ath11k_base *ab, struct hal_srng *srng)
 {
 	lockdep_assert_held(&srng->lock);

drivers/net/wireless/ath/ath11k/hal.h

@@ -946,6 +946,8 @@ u32 *ath11k_hal_srng_dst_peek(struct ath11k_base *ab, struct hal_srng *srng);
 int ath11k_hal_srng_dst_num_free(struct ath11k_base *ab, struct hal_srng *srng,
 				 bool sync_hw_ptr);
 u32 *ath11k_hal_srng_src_peek(struct ath11k_base *ab, struct hal_srng *srng);
+u32 *ath11k_hal_srng_src_next_peek(struct ath11k_base *ab,
+				   struct hal_srng *srng);
 u32 *ath11k_hal_srng_src_get_next_reaped(struct ath11k_base *ab,
 					 struct hal_srng *srng);
 u32 *ath11k_hal_srng_src_reap_next(struct ath11k_base *ab,