ipr: Add delay to ensure coherent dumps.

Add a holding pattern prior to collecting dump data, to wait for the IOA
indication that the Mailbox register is stable and won't change without
an explicit reset.  This ensures we'll be collecting meaningful dump
data, even when dumping right after an adapter reset.

In the event of a timeout, we still force the dump, since a partial dump
still might be useful.
Signed-off-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Acked-by: Brian King <brking@linux.vnet.ibm.com>
Reviewed-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ipr.c

@@ -8277,6 +8277,42 @@ static int ipr_reset_get_unit_check_job(struct ipr_cmnd *ipr_cmd)
 	return IPR_RC_JOB_RETURN;
 }
 
+static int ipr_dump_mailbox_wait(struct ipr_cmnd *ipr_cmd)
+{
+	struct ipr_ioa_cfg *ioa_cfg = ipr_cmd->ioa_cfg;
+
+	ENTER;
+
+	if (ioa_cfg->sdt_state != GET_DUMP)
+		return IPR_RC_JOB_RETURN;
+
+	if (!ioa_cfg->sis64 || !ipr_cmd->u.time_left ||
+	    (readl(ioa_cfg->regs.sense_interrupt_reg) &
+	     IPR_PCII_MAILBOX_STABLE)) {
+
+		if (!ipr_cmd->u.time_left)
+			dev_err(&ioa_cfg->pdev->dev,
+				"Timed out waiting for Mailbox register.\n");
+
+		ioa_cfg->sdt_state = READ_DUMP;
+		ioa_cfg->dump_timeout = 0;
+		if (ioa_cfg->sis64)
+			ipr_reset_start_timer(ipr_cmd, IPR_SIS64_DUMP_TIMEOUT);
+		else
+			ipr_reset_start_timer(ipr_cmd, IPR_SIS32_DUMP_TIMEOUT);
+		ipr_cmd->job_step = ipr_reset_wait_for_dump;
+		schedule_work(&ioa_cfg->work_q);
+
+	} else {
+		ipr_cmd->u.time_left -= IPR_CHECK_FOR_RESET_TIMEOUT;
+		ipr_reset_start_timer(ipr_cmd,
+				      IPR_CHECK_FOR_RESET_TIMEOUT);
+	}
+
+	LEAVE;
+	return IPR_RC_JOB_RETURN;
+}
+
 /**
  * ipr_reset_restore_cfg_space - Restore PCI config space.
  * @ipr_cmd:	ipr command struct
@@ -8326,20 +8362,11 @@ static int ipr_reset_restore_cfg_space(struct ipr_cmnd *ipr_cmd)
 
 	if (ioa_cfg->in_ioa_bringdown) {
 		ipr_cmd->job_step = ipr_ioa_bringdown_done;
+	} else if (ioa_cfg->sdt_state == GET_DUMP) {
+		ipr_cmd->job_step = ipr_dump_mailbox_wait;
+		ipr_cmd->u.time_left = IPR_WAIT_FOR_MAILBOX;
 	} else {
 		ipr_cmd->job_step = ipr_reset_enable_ioa;
-
-		if (GET_DUMP == ioa_cfg->sdt_state) {
-			ioa_cfg->sdt_state = READ_DUMP;
-			ioa_cfg->dump_timeout = 0;
-			if (ioa_cfg->sis64)
-				ipr_reset_start_timer(ipr_cmd, IPR_SIS64_DUMP_TIMEOUT);
-			else
-				ipr_reset_start_timer(ipr_cmd, IPR_SIS32_DUMP_TIMEOUT);
-			ipr_cmd->job_step = ipr_reset_wait_for_dump;
-			schedule_work(&ioa_cfg->work_q);
-			return IPR_RC_JOB_RETURN;
-		}
 	}
 
 	LEAVE;

drivers/scsi/ipr.h

@@ -279,6 +279,9 @@
 #define IPR_IPL_INIT_STAGE_TIME_MASK			0x0000ffff
 #define IPR_PCII_IPL_STAGE_CHANGE			(0x80000000 >> 0)
 
+#define IPR_PCII_MAILBOX_STABLE				(0x80000000 >> 4)
+#define IPR_WAIT_FOR_MAILBOX				(2 * HZ)
+
 #define IPR_PCII_IOA_TRANS_TO_OPER			(0x80000000 >> 0)
 #define IPR_PCII_IOARCB_XFER_FAILED			(0x80000000 >> 3)
 #define IPR_PCII_IOA_UNIT_CHECKED			(0x80000000 >> 4)