linux-kernel - [PATCH 4.19 255/639] scsi: megaraid

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Message-Id: <20200124093118.649741900@linuxfoundation.org>
Date:   Fri, 24 Jan 2020 10:27:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Steve Sistare <steven.sistare@...cle.com>,
        Sumit Saxena <sumit.saxena@...adcom.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 255/639] scsi: megaraid_sas: reduce module load time

From: Steve Sistare <steven.sistare@...cle.com>

[ Upstream commit 31b6a05f86e690e1818116fd23c3be915cc9d9ed ]

megaraid_sas takes 1+ seconds to load while waiting for firmware:

[2.822603] megaraid_sas 0000:03:00.0: Waiting for FW to come to ready state
[3.871003] megaraid_sas 0000:03:00.0: FW now in Ready state

This is due to the following loop in megasas_transition_to_ready(), which
waits a minimum of 1 second, even though the FW becomes ready in tens of
millisecs:

        /*
         * The cur_state should not last for more than max_wait secs
         */
        for (i = 0; i < max_wait; i++) {
                ...
                msleep(1000);
        ...
        dev_info(&instance->pdev->dev, "FW now in Ready state\n");

This is a regression, caused by a change of the msleep granularity from 1
to 1000 due to concern about waiting too long on systems with coarse
jiffies.

To fix, increase iterations and use msleep(20), which results in:

[2.670627] megaraid_sas 0000:03:00.0: Waiting for FW to come to ready state
[2.739386] megaraid_sas 0000:03:00.0: FW now in Ready state

Fixes: fb2f3e96d80f ("scsi: megaraid_sas: Fix msleep granularity")
Signed-off-by: Steve Sistare <steven.sistare@...cle.com>
Acked-by: Sumit Saxena <sumit.saxena@...adcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/scsi/megaraid/megaraid_sas_base.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 2f31d266339f8..99469f9057eea 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -3894,12 +3894,12 @@ megasas_transition_to_ready(struct megasas_instance *instance, int ocr)
 		/*
 		 * The cur_state should not last for more than max_wait secs
 		 */
-		for (i = 0; i < max_wait; i++) {
+		for (i = 0; i < max_wait * 50; i++) {
 			curr_abs_state = instance->instancet->
 				read_fw_status_reg(instance->reg_set);
 
 			if (abs_state == curr_abs_state) {
-				msleep(1000);
+				msleep(20);
 			} else
 				break;
 		}
-- 
2.20.1