scsi: arcmsr: Fix doorbell status being updated late on ARC-1886

It is possible for the IOP to be delayed in updating the doorbell
status. The doorbell status should not be 0 so loop until the value
changes.

Link: https://lore.kernel.org/r/afdfdf7eabecf14632492c4987a6b9ac6312a7ad.camel@areca.com.twSigned-off-by: Nching Huang <ching2048@areca.com.tw>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/arcmsr/arcmsr_hba.c

@@ -2419,10 +2419,17 @@ static void arcmsr_hbaD_doorbell_isr(struct AdapterControlBlock *pACB)
 
 static void arcmsr_hbaE_doorbell_isr(struct AdapterControlBlock *pACB)
 {
-	uint32_t outbound_doorbell, in_doorbell, tmp;
+	uint32_t outbound_doorbell, in_doorbell, tmp, i;
 	struct MessageUnit_E __iomem *reg = pACB->pmuE;
 
-	in_doorbell = readl(&reg->iobound_doorbell);
+	if (pACB->adapter_type == ACB_ADAPTER_TYPE_F) {
+		for (i = 0; i < 5; i++) {
+			in_doorbell = readl(&reg->iobound_doorbell);
+			if (in_doorbell != 0)
+				break;
+		}
+	} else
+		in_doorbell = readl(&reg->iobound_doorbell);
 	outbound_doorbell = in_doorbell ^ pACB->in_doorbell;
 	do {
 		writel(0, &reg->host_int_status); /* clear interrupt */