scsi: arcmsr: Fix clear doorbell queue on ACB_ADAPTER_TYPE_B

Fix clear doorbell queue on ACB_ADAPTER_TYPE_B controller.
Signed-off-by: Ching Huang <ching2048@areca.com.tw>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/arcmsr/arcmsr_hba.c

@@ -4196,10 +4196,19 @@ static void arcmsr_clear_doorbell_queue_buffer(struct AdapterControlBlock *acb)
 
 	case ACB_ADAPTER_TYPE_B: {
 		struct MessageUnit_B *reg = acb->pmuB;
-		/*clear interrupt and message state*/
-		writel(ARCMSR_MESSAGE_INT_CLEAR_PATTERN, reg->iop2drv_doorbell);
+		uint32_t outbound_doorbell, i;
+		writel(ARCMSR_DOORBELL_INT_CLEAR_PATTERN, reg->iop2drv_doorbell);
 		writel(ARCMSR_DRV2IOP_DATA_READ_OK, reg->drv2iop_doorbell);
 		/* let IOP know data has been read */
+		for(i=0; i < 200; i++) {
+			msleep(20);
+			outbound_doorbell = readl(reg->iop2drv_doorbell);
+			if( outbound_doorbell & ARCMSR_IOP2DRV_DATA_WRITE_OK) {
+				writel(ARCMSR_DOORBELL_INT_CLEAR_PATTERN, reg->iop2drv_doorbell);
+				writel(ARCMSR_DRV2IOP_DATA_READ_OK, reg->drv2iop_doorbell);
+			} else
+				break;
+		}
 		}
 		break;
 	case ACB_ADAPTER_TYPE_C: {