[PATCH V3 4/6] PCI: Enable 10-Bit tag support for PCIe Endpoint devices
From: Dongdong Liu <hidden>
Date: 2021-05-12 14:38:10
Also in:
linux-media, linux-pci
Subsystem:
pci subsystem, the rest · Maintainers:
Bjorn Helgaas, Linus Torvalds
10-Bit Tag capability, introduced in PCIe-4.0 increases the total Tag field size from 8 bits to 10 bits. For platforms where the RC supports 10-Bit Tag Completer capability, it is highly recommended for platform firmware or operating software that configures PCIe hierarchies to Set the 10-Bit Tag Requester Enable bit automatically in Endpoints with 10-Bit Tag Requester capability. This enables the important class of 10-Bit Tag capable adapters that send Memory Read Requests only to host memory. Signed-off-by: Dongdong Liu <redacted> --- drivers/pci/probe.c | 36 ++++++++++++++++++++++++++++++++++++ include/linux/pci.h | 2 ++ 2 files changed, 38 insertions(+)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index b9942cc..dfcd3d2 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c@@ -2046,6 +2046,41 @@ int pci_configure_extended_tags(struct pci_dev *dev, void *ign) return 0; } +static void pci_configure_10bit_tags(struct pci_dev *dev) +{ + struct pci_dev *bridge; + + if (!pci_is_pcie(dev)) + return; + + if (!(dev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_COMP)) + return; + + if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) { + dev->ext_10bit_tag = 1; + return; + } + + bridge = pci_upstream_bridge(dev); + if (bridge && bridge->ext_10bit_tag) + dev->ext_10bit_tag = 1; + + /* + * 10-Bit Tag Requester Enable in Device Control 2 Register is RsvdP + * for VF. + */ + if (dev->is_virtfn) + return; + + if (pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT && + dev->ext_10bit_tag == 1 && + (dev->pcie_devcap2 & PCI_EXP_DEVCAP2_10BIT_TAG_REQ)) { + pci_dbg(dev, "enabling 10-Bit Tag Requester\n"); + pcie_capability_set_word(dev, PCI_EXP_DEVCTL2, + PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN); + } +} + /** * pcie_relaxed_ordering_enabled - Probe for PCIe relaxed ordering enable * @dev: PCI device to query
@@ -2182,6 +2217,7 @@ static void pci_configure_device(struct pci_dev *dev) { pci_configure_mps(dev); pci_configure_extended_tags(dev, NULL); + pci_configure_10bit_tags(dev); pci_configure_relaxed_ordering(dev); pci_configure_ltr(dev); pci_configure_eetlp_prefix(dev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2965620..f2b2b5b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h@@ -393,6 +393,8 @@ struct pci_dev { #endif unsigned int eetlp_prefix_path:1; /* End-to-End TLP Prefix */ + unsigned int ext_10bit_tag:1; /* 10-Bit Tag Completer Supported + from root to here */ pci_channel_state_t error_state; /* Current connectivity state */ struct device dev; /* Generic device interface */
--
2.7.4