| Message ID | 20220909202505.314195-3-helgaas@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | PCI/PM: Always disable PTM for all devices during suspend | expand |
On 9/9/22 1:24 PM, Bjorn Helgaas wrote: > From: Bjorn Helgaas <bhelgaas@google.com> > > PTM requires an unbroken path of PTM-supporting devices between the PTM > Root and the ultimate PTM Requester, but if a Switch supports PTM, only the > Upstream Port can have a PTM Capability; the Downstream Ports do not. > > Previously we copied the PTM configuration from the Switch Upstream Port to > the Downstream Ports so dev->ptm_enabled for any device implied that all > the upstream devices support PTM. > > Instead of making it look like Downstream Ports have their own PTM config, > add pci_upstream_ptm(), which returns the upstream device that has a PTM > Capability (either a Root Port or a Switch Upstream Port). > > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> > --- Looks good to me. Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> > drivers/pci/pcie/ptm.c | 39 +++++++++++++++++++++++++-------------- > 1 file changed, 25 insertions(+), 14 deletions(-) > > diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c > index 85382c135885..0df6cdfe38b4 100644 > --- a/drivers/pci/pcie/ptm.c > +++ b/drivers/pci/pcie/ptm.c > @@ -76,6 +76,29 @@ void pci_restore_ptm_state(struct pci_dev *dev) > pci_write_config_word(dev, ptm + PCI_PTM_CTRL, *cap); > } > > +/* > + * If the next upstream device supports PTM, return it; otherwise return > + * NULL. PTM Messages are local, so both link partners must support it. > + */ > +static struct pci_dev *pci_upstream_ptm(struct pci_dev *dev) > +{ > + struct pci_dev *ups = pci_upstream_bridge(dev); > + > + /* > + * Switch Downstream Ports are not permitted to have a PTM > + * capability; their PTM behavior is controlled by the Upstream > + * Port (PCIe r5.0, sec 7.9.16), so if the upstream bridge is a > + * Switch Downstream Port, look up one more level. > + */ > + if (ups && pci_pcie_type(ups) == PCI_EXP_TYPE_DOWNSTREAM) > + ups = pci_upstream_bridge(ups); > + > + if (ups && ups->ptm_cap) > + return ups; > + > + return NULL; > +} > + > void pci_ptm_init(struct pci_dev *dev) > { > u16 ptm; > @@ -95,19 +118,6 @@ void pci_ptm_init(struct pci_dev *dev) > pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END)) > return; > > - /* > - * Switch Downstream Ports are not permitted to have a PTM > - * capability; their PTM behavior is controlled by the Upstream > - * Port (PCIe r5.0, sec 7.9.16). > - */ > - ups = pci_upstream_bridge(dev); > - if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM && > - ups && ups->ptm_enabled) { > - dev->ptm_granularity = ups->ptm_granularity; > - dev->ptm_enabled = 1; > - return; > - } > - > ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); > if (!ptm) > return; > @@ -124,6 +134,7 @@ void pci_ptm_init(struct pci_dev *dev) > * the spec recommendation (PCIe r3.1, sec 7.32.3), select the > * furthest upstream Time Source as the PTM Root. > */ > + ups = pci_upstream_ptm(dev); > if (ups && ups->ptm_enabled) { > ctrl = PCI_PTM_CTRL_ENABLE; > if (ups->ptm_granularity == 0) > @@ -173,7 +184,7 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) > * associate the endpoint with a time source. > */ > if (pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT) { > - ups = pci_upstream_bridge(dev); > + ups = pci_upstream_ptm(dev); > if (!ups || !ups->ptm_enabled) > return -EINVAL; >
diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c index 85382c135885..0df6cdfe38b4 100644 --- a/drivers/pci/pcie/ptm.c +++ b/drivers/pci/pcie/ptm.c @@ -76,6 +76,29 @@ void pci_restore_ptm_state(struct pci_dev *dev) pci_write_config_word(dev, ptm + PCI_PTM_CTRL, *cap); } +/* + * If the next upstream device supports PTM, return it; otherwise return + * NULL. PTM Messages are local, so both link partners must support it. + */ +static struct pci_dev *pci_upstream_ptm(struct pci_dev *dev) +{ + struct pci_dev *ups = pci_upstream_bridge(dev); + + /* + * Switch Downstream Ports are not permitted to have a PTM + * capability; their PTM behavior is controlled by the Upstream + * Port (PCIe r5.0, sec 7.9.16), so if the upstream bridge is a + * Switch Downstream Port, look up one more level. + */ + if (ups && pci_pcie_type(ups) == PCI_EXP_TYPE_DOWNSTREAM) + ups = pci_upstream_bridge(ups); + + if (ups && ups->ptm_cap) + return ups; + + return NULL; +} + void pci_ptm_init(struct pci_dev *dev) { u16 ptm; @@ -95,19 +118,6 @@ void pci_ptm_init(struct pci_dev *dev) pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END)) return; - /* - * Switch Downstream Ports are not permitted to have a PTM - * capability; their PTM behavior is controlled by the Upstream - * Port (PCIe r5.0, sec 7.9.16). - */ - ups = pci_upstream_bridge(dev); - if (pci_pcie_type(dev) == PCI_EXP_TYPE_DOWNSTREAM && - ups && ups->ptm_enabled) { - dev->ptm_granularity = ups->ptm_granularity; - dev->ptm_enabled = 1; - return; - } - ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); if (!ptm) return; @@ -124,6 +134,7 @@ void pci_ptm_init(struct pci_dev *dev) * the spec recommendation (PCIe r3.1, sec 7.32.3), select the * furthest upstream Time Source as the PTM Root. */ + ups = pci_upstream_ptm(dev); if (ups && ups->ptm_enabled) { ctrl = PCI_PTM_CTRL_ENABLE; if (ups->ptm_granularity == 0) @@ -173,7 +184,7 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) * associate the endpoint with a time source. */ if (pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT) { - ups = pci_upstream_bridge(dev); + ups = pci_upstream_ptm(dev); if (!ups || !ups->ptm_enabled) return -EINVAL;