From 2c7e6abd4b167b8fc5b12133322cec93533aeca2 Mon Sep 17 00:00:00 2001
From: imp <imp@FreeBSD.org>
Date: Fri, 26 Oct 2018 14:27:37 +0000
Subject: [PATCH] Put a workaround in for command timeout malfunctioning

At least one NVMe drive has a bug that makeing the Command Time Out
PCIe feature unreliable. The workaround is to disable this
feature. The driver wouldn't deal correctly with a timeout anyway.
Only do this for drives that are known bad.

Sponsored by: Netflix, Inc
Differential Revision: https://reviews.freebsd.org/D17708
---
 sys/dev/nvme/nvme.c         | 20 ++++++++++++++++++++
 sys/dev/nvme/nvme_private.h |  3 ++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/sys/dev/nvme/nvme.c b/sys/dev/nvme/nvme.c
index da3326d32ca8..85820a230782 100644
--- a/sys/dev/nvme/nvme.c
+++ b/sys/dev/nvme/nvme.c
@@ -106,6 +106,7 @@ static struct _pcsid
 	{ 0x05401c5f,		0, 0, "Memblaze Pblaze4", QUIRK_DELAY_B4_CHK_RDY },
 	{ 0xa821144d,		0, 0, "Samsung PM1725", QUIRK_DELAY_B4_CHK_RDY },
 	{ 0xa822144d,		0, 0, "Samsung PM1725a", QUIRK_DELAY_B4_CHK_RDY },
+	{ 0x01161179,		0, 0, "Toshiba XG5", QUIRK_DISABLE_TIMEOUT },
 	{ 0x00000000,		0, 0, NULL  }
 };
 
@@ -278,6 +279,25 @@ nvme_attach(device_t dev)
 		return (status);
 	}
 
+	/*
+	 * Some drives do not implement the completion timeout feature
+	 * correctly. There's a WAR from the manufacturer to just disable it.
+	 * The driver wouldn't respond correctly to a timeout anyway.
+	 */
+	if (ep->quirks & QUIRK_DISABLE_TIMEOUT) {
+		int ptr;
+		uint16_t devctl2;
+
+		status = pci_find_cap(dev, PCIY_EXPRESS, &ptr);
+		if (status) {
+			device_printf(dev, "Can't locate PCIe capability?");
+			return (status);
+		}
+		devctl2 = pci_read_config(dev, ptr + PCIER_DEVICE_CTL2, sizeof(devctl2));
+		devctl2 |= PCIEM_CTL2_COMP_TIMO_DISABLE;
+		pci_write_config(dev, ptr + PCIER_DEVICE_CTL2, devctl2, sizeof(devctl2));
+	}
+
 	/*
 	 * Enable busmastering so the completion status messages can
 	 * be busmastered back to the host.
diff --git a/sys/dev/nvme/nvme_private.h b/sys/dev/nvme/nvme_private.h
index e246136e6701..50e0fdc35af6 100644
--- a/sys/dev/nvme/nvme_private.h
+++ b/sys/dev/nvme/nvme_private.h
@@ -247,7 +247,8 @@ struct nvme_controller {
 
 	uint32_t		ready_timeout_in_ms;
 	uint32_t		quirks;
-#define QUIRK_DELAY_B4_CHK_RDY 1		/* Can't touch MMIO on disable */
+#define	QUIRK_DELAY_B4_CHK_RDY	1		/* Can't touch MMIO on disable */
+#define	QUIRK_DISABLE_TIMEOUT	2		/* Disable broken completion timeout feature */
 
 	bus_space_tag_t		bus_tag;
 	bus_space_handle_t	bus_handle;