[PATCH 4/4][Xenial SRU] scsi: cxlflash: Improve EEH recovery time

[Seth Forshee]

From: "Matthew R. Ochs" <mrochs at linux.vnet.ibm.com>

BugLink: http://bugs.launchpad.net/bugs/1623750

When an EEH occurs during device initialization, the port timeout logic
can cause excessive delays as MMIO reads will fail. Depending on where
they are experienced, these delays can lead to a prolonged reset,
causing an unnecessary triggering of other timeout logic in the SCSI
stack or user applications.

To expedite recovery, the port timeout logic is updated to decay the
timeout at a much faster rate when in the presence of a likely EEH
frozen event.

Signed-off-by: Matthew R. Ochs <mrochs at linux.vnet.ibm.com>
Acked-by: Uma Krishnan <ukrishn at linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
(cherry picked from commit 05dab43230fdc0d14ca885b473a2740fe017ecb1)
Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
---
 drivers/scsi/cxlflash/main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/scsi/cxlflash/main.c b/drivers/scsi/cxlflash/main.c
index 4ef523505364..42970a40d49b 100644
--- a/drivers/scsi/cxlflash/main.c
+++ b/drivers/scsi/cxlflash/main.c
@@ -1040,6 +1040,8 @@ static int wait_port_online(__be64 __iomem *fc_regs, u32 delay_us, u32 nretry)
 	do {
 		msleep(delay_us / 1000);
 		status = readq_be(&fc_regs[FC_MTIP_STATUS / 8]);
+		if (status == U64_MAX)
+			nretry /= 2;
 	} while ((status & FC_MTIP_STATUS_MASK) != FC_MTIP_STATUS_ONLINE &&
 		 nretry--);
 
@@ -1071,6 +1073,8 @@ static int wait_port_offline(__be64 __iomem *fc_regs, u32 delay_us, u32 nretry)
 	do {
 		msleep(delay_us / 1000);
 		status = readq_be(&fc_regs[FC_MTIP_STATUS / 8]);
+		if (status == U64_MAX)
+			nretry /= 2;
 	} while ((status & FC_MTIP_STATUS_MASK) != FC_MTIP_STATUS_OFFLINE &&
 		 nretry--);
 
-- 
2.7.4