On 2021/08/30 23:43, Kate Hsuan wrote: > 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 With "Entire disabling NCQ...", did you mean "Always disabling NCQ" ? If I understand this issue correctly, the explanation should be something like: Always disabling NCQ for Samsung 860/870 SSDs regardless of the host SATA adapter vendor will cause I/O performance degradation with well behaved adapters. To limit the performance impact to AMD adapters, introduce the ATA_HORKAGE_NO_NCQ_ON_AMD flag to force disable NCQ only for these adapters. > 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; > + } > + } It would be really nice to move this hunk into a small helper, something like: static bool ata_dev_check_adapter(struct ata_device *dev, unsigned short vendor_id) The "if" code block then becomes: if ((dev->horkage & ATA_HORKAGE_NONCQ_ON_AMD) && ata_dev_check_adapter(dev, PCI_VENDOR_ID_AMD)) { snprintf(desc, desc_sz, "NCQ (not used)"); return 0; } > + } > + > 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 */ Please add a "_" after "NO", similarly to ATA_HORKAGE_NO_NCQ_TRIM: ATA_HORKAGE_NO_NCQ_ON_AMD = (1 << 27), /* Disable NCQ on AMD chipset */ > > /* DMA mask for user DMA control: User visible values; DO NOT > renumber */ > -- Damien Le Moal Western Digital Research
