[PATCH v2 08/14] wifi: ath12k: Add drop descriptor handling for monitor ring

[P Praneesh]

When monitor block in Hardware experiences internal backpressure, a ring
entry with the EMPTY_DESC reason is received in the monitor destination
ring descriptor. The cookie field for this corresponding entry is invalid.
Currently driver attempts to process this cookie resulting in invalid
buf_id warning logs flooding the console. To fix this, skip processing the
destination descriptor when the EMPTY_DESCRIPTOR bit is set to true in ring
descriptor, thereby avoiding the processing of junk cookies.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Signed-off-by: P Praneesh <quic_ppranees at quicinc.com>
---
 drivers/net/wireless/ath/ath12k/dp_mon.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/wireless/ath/ath12k/dp_mon.c b/drivers/net/wireless/ath/ath12k/dp_mon.c
index 236456b02198..bf43ef2b6b39 100644
--- a/drivers/net/wireless/ath/ath12k/dp_mon.c
+++ b/drivers/net/wireless/ath/ath12k/dp_mon.c
@@ -2347,6 +2347,14 @@ int ath12k_dp_mon_srng_process(struct ath12k *ar, int *budget,
 		if (unlikely(!mon_dst_desc))
 			break;
 
+		/* In case of empty descriptor, the cookie in the ring descriptor
+		 * is invalid. Therefore, this entry is skipped, and ring processing
+		 * continues.
+		 */
+		info0 = le32_to_cpu(mon_dst_desc->info0);
+		if (u32_get_bits(info0, HAL_MON_DEST_INFO0_EMPTY_DESC))
+			goto move_next;
+
 		cookie = le32_to_cpu(mon_dst_desc->cookie);
 		buf_id = u32_get_bits(cookie, DP_RXDMA_BUF_COOKIE_BUF_ID);
 
-- 
2.34.1