[PATCH v3 1/1] libata: Add ATA_HORKAGE_NONCQ_ON_AMD for Samsung 860 and 870 SSD.

[Kate Hsuan]

Many users are reporting that the Samsung 860 and 870 SSD are having
various issues when combined with AMD SATA controllers and only
completely disabling NCQ helps to avoid these issues.

Entire disabling NCQ for Samsugn 860/870 SSD will cause I/O performance
drop. In this case, a flag ATA_HORKAGE_NONCQ_ON_AMD is introduced to
used to perform an additional check for these SSDs. If it finds it's
parent ATA controller is AMD, the NCQ will be disabled. Otherwise, the
NCQ is kept to enable.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=201693
Signed-off-by: Kate Hsuan <hpa@xxxxxxxxxx>
---
 drivers/ata/libata-core.c | 24 ++++++++++++++++++++++--
 include/linux/libata.h    |  1 +
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index c861c93d1e84..36c62f758b73 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2190,6 +2190,8 @@ static int ata_dev_config_ncq(struct ata_device *dev,
 			       char *desc, size_t desc_sz)
 {
 	struct ata_port *ap = dev->link->ap;
+	struct pci_dev *pcidev = NULL;
+	struct device *parent_dev = NULL;
 	int hdepth = 0, ddepth = ata_id_queue_depth(dev->id);
 	unsigned int err_mask;
 	char *aa_desc = "";
@@ -2204,6 +2206,22 @@ static int ata_dev_config_ncq(struct ata_device *dev,
 		snprintf(desc, desc_sz, "NCQ (not used)");
 		return 0;
 	}
+
+	if (dev->horkage & ATA_HORKAGE_NONCQ_ON_AMD) {
+		for (parent_dev = dev->tdev.parent; parent_dev != NULL;
+		    parent_dev = parent_dev->parent) {
+			if (dev_is_pci(parent_dev)) {
+				pcidev = to_pci_dev(parent_dev);
+				if (pcidev->vendor == PCI_VENDOR_ID_AMD) {
+					snprintf(desc, desc_sz,
+						 "NCQ (not used)");
+					return 0;
+				}
+			break;
+			}
+		}
+	}
+
 	if (ap->flags & ATA_FLAG_NCQ) {
 		hdepth = min(ap->scsi_host->can_queue, ATA_MAX_QUEUE);
 		dev->flags |= ATA_DFLAG_NCQ;
@@ -3971,9 +3989,11 @@ static const struct ata_blacklist_entry ata_device_blacklist [] = {
 	{ "Samsung SSD 850*",		NULL,	ATA_HORKAGE_NO_NCQ_TRIM |
 						ATA_HORKAGE_ZERO_AFTER_TRIM, },
 	{ "Samsung SSD 860*",           NULL,   ATA_HORKAGE_NO_NCQ_TRIM |
-						ATA_HORKAGE_ZERO_AFTER_TRIM, },
+						ATA_HORKAGE_ZERO_AFTER_TRIM |
+						ATA_HORKAGE_NONCQ_ON_AMD, },
 	{ "Samsung SSD 870*",           NULL,   ATA_HORKAGE_NO_NCQ_TRIM |
-						ATA_HORKAGE_ZERO_AFTER_TRIM, },
+						ATA_HORKAGE_ZERO_AFTER_TRIM |
+						ATA_HORKAGE_NONCQ_ON_AMD, },
 	{ "FCCT*M500*",			NULL,	ATA_HORKAGE_NO_NCQ_TRIM |
 						ATA_HORKAGE_ZERO_AFTER_TRIM, },
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 860e63f5667b..42e16114e91f 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -426,6 +426,7 @@ enum {
 	ATA_HORKAGE_NOTRIM	= (1 << 24),	/* don't use TRIM */
 	ATA_HORKAGE_MAX_SEC_1024 = (1 << 25),	/* Limit max sects to 1024 */
 	ATA_HORKAGE_MAX_TRIM_128M = (1 << 26),	/* Limit max trim size to 128M */
+	ATA_HORKAGE_NONCQ_ON_AMD = (1 << 27),	/* Disable NCQ on AMD chipset */
 
 	 /* DMA mask for user DMA control: User visible values; DO NOT
 	    renumber */
-- 
2.31.1