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 <liudongdong3@xxxxxxxxxx>
---
drivers/pci/probe.c | 39 +++++++++++++++++++++++++++++++++++++++
include/linux/pci.h | 1 +
2 files changed, 40 insertions(+)
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 953f15a..3efe1cc 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2051,6 +2051,44 @@ int pci_configure_extended_tags(struct pci_dev *dev, void *ign)
return 0;
}
+static void pci_configure_10bit_tags(struct pci_dev *dev)
+{
+ u32 cap;
+ int ret;
+ struct pci_dev *bridge;
+
+ if (!pci_is_pcie(dev))
+ return;
+
+ ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
+ if (ret)
+ return;
+
+ if (!(cap & PCI_EXP_DEVCAP2_10BIT_TAG_COMP))
+ return;
+
+ if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) {
+ dev->ext_10bit_tag_comp_path = 1;
+ return;
+ }
+
+ bridge = pci_upstream_bridge(dev);
+ if (bridge && bridge->ext_10bit_tag_comp_path)
+ dev->ext_10bit_tag_comp_path = 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_comp_path == 1 &&
+ (cap & PCI_EXP_DEVCAP2_10BIT_TAG_REQ)) {
+ pci_info(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
@@ -2190,6 +2228,7 @@ 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 86c799c..1cd0ee0 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -390,6 +390,7 @@ struct pci_dev {
#endif
unsigned int eetlp_prefix_path:1; /* End-to-End TLP Prefix */
+ unsigned int ext_10bit_tag_comp_path: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 */
--
1.9.1
