qcacmn: IPA WAR for WB2SW release ring

WAR for IPA_OFFLOAD case. In IPA_OFFLOAD case, host provides buffers in
the WBM2SW release ring designated for IPA for TX. So this ring is used
to release TX completions into, by WBM, and also by IPA to pick up
buffers from, for TX.

In some cases, its observed that when  WBM tries to release a buffer
into this ring, however the ring is full. This causes back pressure,
resulting in a FW crash.

By leaving some entries with no buffers attached, WBM will be able to
write to the ring, and from dumps we can figure out the buffer which is
causing this issue.

Change-Id: Ia0450d36dec643f2631fea13cb0b8facba7425b8
CRs-Fixed: 2535170

dp/wifi3.0/dp_ipa.c

@@ -34,6 +34,15 @@
 /* Hard coded config parameters until dp_ops_cfg.cfg_attach implemented */
 #define CFG_IPA_UC_TX_BUF_SIZE_DEFAULT            (2048)
 
+/* WAR for IPA_OFFLOAD case. In some cases, its observed that WBM tries to
+ * release a buffer into WBM2SW RELEASE ring for IPA, and the ring is full.
+ * This causes back pressure, resulting in a FW crash.
+ * By leaving some entries with no buffer attached, WBM will be able to write
+ * to the ring, and from dumps we can figure out the buffer which is causing
+ * this issue.
+ */
+#define DP_IPA_WAR_WBM2SW_REL_RING_NO_BUF_ENTRIES 16
+
 static QDF_STATUS __dp_ipa_handle_buf_smmu_mapping(struct dp_soc *soc,
 						   qdf_nbuf_t nbuf,
 						   bool create)
@@ -249,6 +258,7 @@ static int dp_tx_ipa_uc_attach(struct dp_soc *soc, struct dp_pdev *pdev)
 	int num_entries;
 	qdf_nbuf_t nbuf;
 	int retval = QDF_STATUS_SUCCESS;
+	int max_alloc_count = 0;
 
 	/*
 	 * Uncomment when dp_ops_cfg.cfg_attach is implemented
@@ -262,17 +272,21 @@ static int dp_tx_ipa_uc_attach(struct dp_soc *soc, struct dp_pdev *pdev)
 			    &srng_params);
 	num_entries = srng_params.num_entries;
 
-	QDF_TRACE(QDF_MODULE_ID_DP, QDF_TRACE_LEVEL_INFO,
-		  "%s: requested %d buffers to be posted to wbm ring",
-		   __func__, num_entries);
+	max_alloc_count =
+		num_entries - DP_IPA_WAR_WBM2SW_REL_RING_NO_BUF_ENTRIES;
+	if (max_alloc_count <= 0) {
+		dp_err("incorrect value for buffer count %u", max_alloc_count);
+		return -EINVAL;
+	}
+
+	dp_info("requested %d buffers to be posted to wbm ring",
+		max_alloc_count);
 
 	soc->ipa_uc_tx_rsc.tx_buf_pool_vaddr_unaligned =
 		qdf_mem_malloc(num_entries *
 		sizeof(*soc->ipa_uc_tx_rsc.tx_buf_pool_vaddr_unaligned));
 	if (!soc->ipa_uc_tx_rsc.tx_buf_pool_vaddr_unaligned) {
-		QDF_TRACE(QDF_MODULE_ID_DP, QDF_TRACE_LEVEL_ERROR,
-			  "%s: IPA WBM Ring Tx buf pool vaddr alloc fail",
-			  __func__);
+		dp_err("IPA WBM Ring Tx buf pool vaddr alloc fail");
 		return -ENOMEM;
 	}
 
@@ -280,13 +294,14 @@ static int dp_tx_ipa_uc_attach(struct dp_soc *soc, struct dp_pdev *pdev)
 				       hal_srng_to_hal_ring_handle(wbm_srng));
 
 	/*
-	 * Allocate Tx buffers as many as possible
+	 * Allocate Tx buffers as many as possible.
+	 * Leave DP_IPA_WAR_WBM2SW_REL_RING_NO_BUF_ENTRIES empty
 	 * Populate Tx buffers into WBM2IPA ring
 	 * This initial buffer population will simulate H/W as source ring,
 	 * and update HP
 	 */
 	for (tx_buffer_count = 0;
-		tx_buffer_count < num_entries - 1; tx_buffer_count++) {
+		tx_buffer_count < max_alloc_count - 1; tx_buffer_count++) {
 		nbuf = qdf_nbuf_alloc(soc->osdev, alloc_size, 0, 256, FALSE);
 		if (!nbuf)
 			break;
@@ -325,13 +340,9 @@ static int dp_tx_ipa_uc_attach(struct dp_soc *soc, struct dp_pdev *pdev)
 	soc->ipa_uc_tx_rsc.alloc_tx_buf_cnt = tx_buffer_count;
 
 	if (tx_buffer_count) {
-		QDF_TRACE(QDF_MODULE_ID_DP, QDF_TRACE_LEVEL_INFO,
-			  "%s: IPA WDI TX buffer: %d allocated",
-			  __func__, tx_buffer_count);
+		dp_info("IPA WDI TX buffer: %d allocated", tx_buffer_count);
 	} else {
-		QDF_TRACE(QDF_MODULE_ID_DP, QDF_TRACE_LEVEL_ERROR,
-			  "%s: No IPA WDI TX buffer allocated",
-			  __func__);
+		dp_err("No IPA WDI TX buffer allocated!");
 		qdf_mem_free(soc->ipa_uc_tx_rsc.tx_buf_pool_vaddr_unaligned);
 		soc->ipa_uc_tx_rsc.tx_buf_pool_vaddr_unaligned = NULL;
 		retval = -ENOMEM;