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| author | Bjorn Helgaas <bhelgaas@google.com> | 2020-05-21 15:40:07 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-06-25 15:41:54 +0200 |
| commit | 6ccae103c95b44c7840b04ff73b6d3ef4c522fed (patch) | |
| tree | afef833ebb70d1df4387c20611e11cd033156cca /drivers/pci/pcie | |
| parent | 2296eda690db1c4619370d6c4f2624db6b3b3acd (diff) | |
| download | linux-rt-6ccae103c95b44c7840b04ff73b6d3ef4c522fed.tar.gz | |
PCI/PTM: Inherit Switch Downstream Port PTM settings from Upstream Port
[ Upstream commit 7b38fd9760f51cc83d80eed2cfbde8b5ead9e93a ]
Except for Endpoints, we enable PTM at enumeration-time. Previously we did
not account for the fact that 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). Since Downstream Ports don't have a PTM
capability, we did not mark them as "ptm_enabled", which meant that
pci_enable_ptm() on an Endpoint failed because there was no PTM path to it.
Mark Downstream Ports as "ptm_enabled" if their Upstream Port has PTM
enabled.
Fixes: eec097d43100 ("PCI: Add pci_enable_ptm() for drivers to enable PTM on endpoints")
Reported-by: Aditya Paluri <Venkata.AdityaPaluri@synopsys.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/pci/pcie')
| -rw-r--r-- | drivers/pci/pcie/ptm.c | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c index 3008bba360f3..ec6f6213960b 100644 --- a/drivers/pci/pcie/ptm.c +++ b/drivers/pci/pcie/ptm.c @@ -47,10 +47,6 @@ void pci_ptm_init(struct pci_dev *dev) if (!pci_is_pcie(dev)) return; - pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); - if (!pos) - return; - /* * Enable PTM only on interior devices (root ports, switch ports, * etc.) on the assumption that it causes no link traffic until an @@ -60,6 +56,23 @@ 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; + } + + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); + if (!pos) + return; + pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap); local_clock = (cap & PCI_PTM_GRANULARITY_MASK) >> 8; @@ -69,7 +82,6 @@ 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_bridge(dev); if (ups && ups->ptm_enabled) { ctrl = PCI_PTM_CTRL_ENABLE; if (ups->ptm_granularity == 0) |