PCIe spec 5.0r1.0 section 2.2.6.2 implementation note, In configurations
where a Requester with 10-Bit Tag Requester capability needs to target
multiple Completers, one needs to ensure that the Requester sends 10-Bit
Tag Requests only to Completers that have 10-Bit Tag Completer capability.
So we enable 10-Bit Tag Requester for root port only when the devices
under the root port support 10-Bit Tag Completer.
Signed-off-by: Dongdong Liu <liudongdong3@xxxxxxxxxx>
---
drivers/pci/pci.h | 2 +
drivers/pci/pcie/portdrv_pci.c | 3 ++
drivers/pci/probe.c | 86 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 91 insertions(+)
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index ef7c466..056b73d 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -459,6 +459,7 @@ static inline void pci_dpc_init(struct pci_dev *pdev) {}
void pcie_walk_rcec(struct pci_dev *rcec,
int (*cb)(struct pci_dev *, void *),
void *userdata);
+void pci_configure_rp_10bit_tag(struct pci_dev *dev);
#else
static inline void pci_rcec_init(struct pci_dev *dev) {}
static inline void pci_rcec_exit(struct pci_dev *dev) {}
@@ -466,6 +467,7 @@ static inline void pcie_link_rcec(struct pci_dev *rcec) {}
static inline void pcie_walk_rcec(struct pci_dev *rcec,
int (*cb)(struct pci_dev *, void *),
void *userdata) {}
+static inline void pci_configure_rp_10bit_tag(struct pci_dev *dev) {}
#endif
#ifdef CONFIG_PCI_ATS
diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
index c7ff1ee..3af4733 100644
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -111,6 +111,9 @@ static int pcie_portdrv_probe(struct pci_dev *dev,
(type != PCI_EXP_TYPE_RC_EC)))
return -ENODEV;
+ if (type == PCI_EXP_TYPE_ROOT_PORT)
+ pci_configure_rp_10bit_tag(dev);
+
if (type == PCI_EXP_TYPE_RC_EC)
pcie_link_rcec(dev);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 3efe1cc..73105c3 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2051,6 +2051,92 @@ int pci_configure_extended_tags(struct pci_dev *dev, void *ign)
return 0;
}
+static int pci_10bit_tag_comp_support(struct pci_dev *dev, void *data)
+{
+ u8 *support = data;
+ int ret;
+ u32 cap;
+
+ if (*support == 0)
+ return 0;
+
+ if (!pci_is_pcie(dev)) {
+ *support = 0;
+ return 0;
+ }
+
+ /*
+ * PCIe spec 5.0r1.0 section 2.2.6.2 implementation note
+ * For configurations where a Requester with 10-Bit Tag Requester capability
+ * targets Completers where some do and some do not have 10-Bit Tag
+ * Completer capability, how the Requester determines which NPRs include
+ * 10-Bit Tags is outside the scope of this specification. So we do not consider
+ * hotplug scenario.
+ */
+ if (dev->is_hotplug_bridge) {
+ *support = 0;
+ return 0;
+ }
+
+ ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
+ if (ret) {
+ *support = 0;
+ return 0;
+ }
+
+ if (!(cap & PCI_EXP_DEVCAP2_10BIT_TAG_COMP)) {
+ *support = 0;
+ return 0;
+ }
+
+
+ return 0;
+}
+
+void pci_configure_rp_10bit_tag(struct pci_dev *dev)
+{
+ u8 support = 1;
+ u32 cap;
+ int ret;
+
+ if (!pci_is_pcie(dev))
+ return;
+
+ if (pci_pcie_type(dev) != PCI_EXP_TYPE_ROOT_PORT)
+ return;
+
+ if (dev->subordinate == NULL)
+ return;
+
+ pci_10bit_tag_comp_support(dev, &support);
+ if (!support)
+ return;
+
+ /*
+ * PCIe spec 5.0r1.0 section 2.2.6.2 implementation note
+ * In configurations where a Requester with 10-Bit Tag Requester capability
+ * needs to target multiple Completers, one needs to ensure that the
+ * Requester sends 10-Bit Tag Requests only to Completers that have 10-Bit
+ * Tag Completer capability. So we enable 10-Bit Tag Requester for root port
+ * only when the devices under the root port support 10-Bit Tag Completer.
+ */
+ pci_walk_bus(dev->subordinate, pci_10bit_tag_comp_support, &support);
+ if (!support)
+ return;
+
+ ret = pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
+ if (ret)
+ return;
+
+ if (!(cap & PCI_EXP_DEVCAP2_10BIT_TAG_REQ))
+ return;
+
+ pci_info(dev, "enabling 10-Bit Tag Requester\n");
+ pcie_capability_set_word(dev, PCI_EXP_DEVCTL2,
+ PCI_EXP_DEVCTL2_10BIT_TAG_REQ_EN);
+}
+
+
static void pci_configure_10bit_tags(struct pci_dev *dev)
{
u32 cap;
--
1.9.1
