scsi: megaraid_sas: Retry with reduced queue depth when alloc fails for higher QD

In certain cases, the host memory is limited and with FW supporting
higher queue depths there are increasing chances of IO request frame
allocation failures that we are seeing. In case of request frame
allocation failures, retry allocation with reduced queue depth (in steps
of 64) to continue to configure the controller with a reduced
performance rather than failing load.
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/megaraid/megaraid_sas_fusion.c

@@ -96,6 +96,8 @@ extern unsigned int resetwaittime;
 extern unsigned int dual_qdepth_disable;
 static void megasas_free_rdpq_fusion(struct megasas_instance *instance);
 static void megasas_free_reply_fusion(struct megasas_instance *instance);
+static inline
+void megasas_configure_queue_sizes(struct megasas_instance *instance);
 
 
 
@@ -254,8 +256,8 @@ megasas_fusion_update_can_queue(struct megasas_instance *instance, int fw_boot_c
 			(instance->instancet->read_fw_status_reg(reg_set) & 0x00FFFF) - MEGASAS_FUSION_IOCTL_CMDS;
 
 	dev_info(&instance->pdev->dev,
-			"Current firmware maximum commands: %d\t LDIO threshold: %d\n",
-			cur_max_fw_cmds, ldio_threshold);
+		 "Current firmware supports maximum commands: %d\t LDIO thershold: %d\n",
+		 cur_max_fw_cmds, ldio_threshold);
 
 	if (fw_boot_context == OCR_CONTEXT) {
 		cur_max_fw_cmds = cur_max_fw_cmds - 1;
@@ -283,19 +285,7 @@ megasas_fusion_update_can_queue(struct megasas_instance *instance, int fw_boot_c
 		* does not exceed max cmds that the FW can support
 		*/
 		instance->max_fw_cmds = instance->max_fw_cmds-1;
-
-		instance->max_scsi_cmds = instance->max_fw_cmds -
-				(MEGASAS_FUSION_INTERNAL_CMDS +
-				MEGASAS_FUSION_IOCTL_CMDS);
-		instance->cur_can_queue = instance->max_scsi_cmds;
-		instance->host->can_queue = instance->cur_can_queue;
 	}
-
-	if (instance->adapter_type == VENTURA_SERIES)
-		instance->max_mpt_cmds =
-		instance->max_fw_cmds * RAID_1_PEER_CMDS;
-	else
-		instance->max_mpt_cmds = instance->max_fw_cmds;
 }
 /**
  * megasas_free_cmds_fusion -	Free all the cmds in the free cmd pool
@@ -468,16 +458,7 @@ megasas_alloc_request_fusion(struct megasas_instance *instance)
 
 	fusion = instance->ctrl_context;
 
-	fusion->req_frames_desc =
-		dma_alloc_coherent(&instance->pdev->dev,
-			fusion->request_alloc_sz,
-			&fusion->req_frames_desc_phys, GFP_KERNEL);
-	if (!fusion->req_frames_desc) {
-		dev_err(&instance->pdev->dev,
-			"Failed from %s %d\n",  __func__, __LINE__);
-		return -ENOMEM;
-	}
-
+retry_alloc:
 	fusion->io_request_frames_pool =
 			dma_pool_create("mr_ioreq", &instance->pdev->dev,
 				fusion->io_frames_alloc_sz, 16, 0);
@@ -492,10 +473,28 @@ megasas_alloc_request_fusion(struct megasas_instance *instance)
 			dma_pool_alloc(fusion->io_request_frames_pool,
 				GFP_KERNEL, &fusion->io_request_frames_phys);
 	if (!fusion->io_request_frames) {
+		if (instance->max_fw_cmds >= (MEGASAS_REDUCE_QD_COUNT * 2)) {
+			instance->max_fw_cmds -= MEGASAS_REDUCE_QD_COUNT;
+			dma_pool_destroy(fusion->io_request_frames_pool);
+			megasas_configure_queue_sizes(instance);
+			goto retry_alloc;
+		} else {
+			dev_err(&instance->pdev->dev,
+				"Failed from %s %d\n",  __func__, __LINE__);
+			return -ENOMEM;
+		}
+	}
+
+	fusion->req_frames_desc =
+		dma_alloc_coherent(&instance->pdev->dev,
+				   fusion->request_alloc_sz,
+				   &fusion->req_frames_desc_phys, GFP_KERNEL);
+	if (!fusion->req_frames_desc) {
 		dev_err(&instance->pdev->dev,
 			"Failed from %s %d\n",  __func__, __LINE__);
 		return -ENOMEM;
 	}
+
 	return 0;
 }
 
@@ -664,9 +663,6 @@ megasas_alloc_cmds_fusion(struct megasas_instance *instance)
 
 	fusion = instance->ctrl_context;
 
-	if (megasas_alloc_cmdlist_fusion(instance))
-		goto fail_exit;
-
 	if (megasas_alloc_request_fusion(instance))
 		goto fail_exit;
 
@@ -677,6 +673,11 @@ megasas_alloc_cmds_fusion(struct megasas_instance *instance)
 		if (megasas_alloc_reply_fusion(instance))
 			goto fail_exit;
 
+	if (megasas_alloc_cmdlist_fusion(instance))
+		goto fail_exit;
+
+	dev_info(&instance->pdev->dev, "Configured max firmware commands: %d\n",
+		 instance->max_fw_cmds);
 
 	/* The first 256 bytes (SMID 0) is not used. Don't add to the cmd list */
 	io_req_base = fusion->io_request_frames + MEGA_MPI2_RAID_DEFAULT_IO_FRAME_SIZE;
@@ -1325,6 +1326,44 @@ static inline int megasas_allocate_raid_maps(struct megasas_instance *instance)
 	return -ENOMEM;
 }
 
+/**
+ * megasas_configure_queue_sizes -	Calculate size of request desc queue,
+ *					reply desc queue,
+ *					IO request frame queue, set can_queue.
+ * @instance:				Adapter soft state
+ * @return:				void
+ */
+static inline
+void megasas_configure_queue_sizes(struct megasas_instance *instance)
+{
+	struct fusion_context *fusion;
+	u16 max_cmd;
+
+	fusion = instance->ctrl_context;
+	max_cmd = instance->max_fw_cmds;
+
+	if (instance->adapter_type == VENTURA_SERIES)
+		instance->max_mpt_cmds = instance->max_fw_cmds * RAID_1_PEER_CMDS;
+	else
+		instance->max_mpt_cmds = instance->max_fw_cmds;
+
+	instance->max_scsi_cmds = instance->max_fw_cmds -
+			(MEGASAS_FUSION_INTERNAL_CMDS +
+			MEGASAS_FUSION_IOCTL_CMDS);
+	instance->cur_can_queue = instance->max_scsi_cmds;
+	instance->host->can_queue = instance->cur_can_queue;
+
+	fusion->reply_q_depth = 2 * ((max_cmd + 1 + 15) / 16) * 16;
+
+	fusion->request_alloc_sz = sizeof(union MEGASAS_REQUEST_DESCRIPTOR_UNION) *
+					  instance->max_mpt_cmds;
+	fusion->reply_alloc_sz = sizeof(union MPI2_REPLY_DESCRIPTORS_UNION) *
+					(fusion->reply_q_depth);
+	fusion->io_frames_alloc_sz = MEGA_MPI2_RAID_DEFAULT_IO_FRAME_SIZE +
+		(MEGA_MPI2_RAID_DEFAULT_IO_FRAME_SIZE
+		 * (instance->max_mpt_cmds + 1)); /* Extra 1 for SMID 0 */
+}
+
 static int megasas_alloc_ioc_init_frame(struct megasas_instance *instance)
 {
 	struct fusion_context *fusion;
@@ -1386,7 +1425,6 @@ megasas_init_adapter_fusion(struct megasas_instance *instance)
 {
 	struct megasas_register_set __iomem *reg_set;
 	struct fusion_context *fusion;
-	u16 max_cmd;
 	u32 scratch_pad_2;
 	int i = 0, count;
 
@@ -1402,17 +1440,7 @@ megasas_init_adapter_fusion(struct megasas_instance *instance)
 	instance->max_mfi_cmds =
 		MEGASAS_FUSION_INTERNAL_CMDS + MEGASAS_FUSION_IOCTL_CMDS;
 
-	max_cmd = instance->max_fw_cmds;
-
-	fusion->reply_q_depth = 2 * (((max_cmd + 1 + 15)/16)*16);
-
-	fusion->request_alloc_sz =
-	sizeof(union MEGASAS_REQUEST_DESCRIPTOR_UNION) * instance->max_mpt_cmds;
-	fusion->reply_alloc_sz = sizeof(union MPI2_REPLY_DESCRIPTORS_UNION)
-		*(fusion->reply_q_depth);
-	fusion->io_frames_alloc_sz = MEGA_MPI2_RAID_DEFAULT_IO_FRAME_SIZE +
-		(MEGA_MPI2_RAID_DEFAULT_IO_FRAME_SIZE
-		* (instance->max_mpt_cmds + 1)); /* Extra 1 for SMID 0 */
+	megasas_configure_queue_sizes(instance);
 
 	scratch_pad_2 = readl(&instance->reg_set->outbound_scratch_pad_2);
 	/* If scratch_pad_2 & MEGASAS_MAX_CHAIN_SIZE_UNITS_MASK is set,

drivers/scsi/megaraid/megaraid_sas_fusion.h

@@ -103,6 +103,7 @@ enum MR_RAID_FLAGS_IO_SUB_TYPE {
 #define THRESHOLD_REPLY_COUNT 50
 #define RAID_1_PEER_CMDS 2
 #define JBOD_MAPS_COUNT	2
+#define MEGASAS_REDUCE_QD_COUNT 64
 #define IOC_INIT_FRAME_SIZE 4096
 
 /*