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PCI/ATS: Disable PF/VF ATS service independently

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Previously we didn't disable the PF ATS until all associated VFs had
disabled it.  But per PCIe spec r5.0, sec 9.3.7.8, the ATS Capability in
VFs and associated PFs may be enabled independently.  Leaving ATS enabled
in the PF unnecessarily may have power and performance impacts.

Remove this dependency logic in the ATS enable/disable code.

[bhelgaas: commit log]
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Link: https://lore.kernel.org/r/8163ab8fa66afd2cba514ae95d29ab12104781aa.1567029860.git.sathyanarayanan.kuppuswamy@linux.intel.com
Link: https://lore.kernel.org/r/20190905193146.90250-4-helgaas@kernel.org
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
This commit is contained in:
Kuppuswamy Sathyanarayanan 2019-09-05 14:31:44 -05:00 committed by Bjorn Helgaas
parent 2b0ae7cc3b
commit 3ad6219209
2 changed files with 0 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/pci/ats.c
View File

@ -60,8 +60,6 @@ int pci_enable_ats(struct pci_dev *dev, int ps)
pdev = pci_physfn(dev);
if (pdev->ats_stu != ps)
return -EINVAL;
atomic_inc(&pdev->ats_ref_cnt); /* count enabled VFs */
} else {
dev->ats_stu = ps;
ctrl |= PCI_ATS_CTRL_STU(dev->ats_stu - PCI_ATS_MIN_STU);
@ -79,20 +77,11 @@ EXPORT_SYMBOL_GPL(pci_enable_ats);
*/
void pci_disable_ats(struct pci_dev *dev)
{
struct pci_dev *pdev;
u16 ctrl;
if (WARN_ON(!dev->ats_enabled))
return;
if (atomic_read(&dev->ats_ref_cnt))
return; /* VFs still enabled */
if (dev->is_virtfn) {
pdev = pci_physfn(dev);
atomic_dec(&pdev->ats_ref_cnt);
}
pci_read_config_word(dev, dev->ats_cap + PCI_ATS_CTRL, &ctrl);
ctrl &= ~PCI_ATS_CTRL_ENABLE;
pci_write_config_word(dev, dev->ats_cap + PCI_ATS_CTRL, ctrl);

1
include/linux/pci.h
View File

@ -452,7 +452,6 @@ struct pci_dev {
};
u16 ats_cap; /* ATS Capability offset */
u8 ats_stu; /* ATS Smallest Translation Unit */
atomic_t ats_ref_cnt; /* Number of VFs with ATS enabled */
#endif
#ifdef CONFIG_PCI_PRI
u32 pri_reqs_alloc; /* Number of PRI requests allocated */