From: Kevin.xie <kevin.xie@starfivetech.com>
Date: Thu, 24 Nov 2022 08:59:12 +0000 (+0800)
Subject: drivers: nvme: Add precheck and delay for CQE pending status.
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a8700cb09c164a0c0bcc07b1351802afabe78ea7;p=platform%2Fkernel%2Flinux-starfive.git

drivers: nvme: Add precheck and delay for CQE pending status.

To workaroud the NVMe I/O timeout problem in bootup S10udev case
which caused by the CQE update lantancy.

Signed-off-by: Kevin.xie <kevin.xie@starfivetech.com>
---

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 149ecf7..f9321fa 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -26,6 +26,7 @@
 #include <linux/io-64-nonatomic-hi-lo.h>
 #include <linux/sed-opal.h>
 #include <linux/pci-p2pdma.h>
+#include <linux/delay.h>
 
 #include "trace.h"
 #include "nvme.h"
@@ -1042,6 +1043,15 @@ static inline int nvme_process_cq(struct nvme_queue *nvmeq)
 {
 	int found = 0;
 
+	/*
+	 * In some cases, such as udev trigger, cqe status may update
+	 * a little bit later than MSI, which cause an irq handle missing.
+	 * To workaound, here we will prefetch the status first, and wait
+	 * 1us if we get nothing.
+	 */
+	if (!nvme_cqe_pending(nvmeq))
+		udelay(1);
+
 	while (nvme_cqe_pending(nvmeq)) {
 		found++;
 		/*