On 2024-10-02 5:59 pm, Wei Huang wrote:
[...]
+/**
+ * pcie_tph_set_st_entry() - Set Steering Tag in the ST table entry
+ * @pdev: PCI device
+ * @index: ST table entry index
+ * @tag: Steering Tag to be written
+ *
+ * This function will figure out the proper location of ST table, either in the
+ * MSI-X table or in the TPH Extended Capability space, and write the Steering
+ * Tag into the ST entry pointed by index.
+ *
+ * Returns: 0 if success, otherwise negative value (-errno)
+ */
+int pcie_tph_set_st_entry(struct pci_dev *pdev, unsigned int index, u16 tag)
+{
+ u32 loc;
+ int err = 0;
+
+ if (!pdev->tph_cap)
+ return -EINVAL;
+
+ if (!pdev->tph_enabled)
+ return -EINVAL;
+
+ /* No need to write tag if device is in "No ST Mode" */
+ if (pdev->tph_mode == PCI_TPH_ST_NS_MODE)
+ return 0;
+
+ /* Disable TPH before updating ST to avoid potential instability as
+ * cautioned in PCIe r6.2, sec 6.17.3, "ST Modes of Operation"
+ */
+ set_ctrl_reg_req_en(pdev, PCI_TPH_REQ_DISABLE);
+
+ loc = get_st_table_loc(pdev);
+ /* Convert loc to match with PCI_TPH_LOC_* defined in pci_regs.h */
+ loc = FIELD_PREP(PCI_TPH_CAP_LOC_MASK, loc);
+
+ switch (loc) {
+ case PCI_TPH_LOC_MSIX:
+ err = write_tag_to_msix(pdev, index, tag);
+ break;
+ case PCI_TPH_LOC_CAP:
+ err = write_tag_to_st_table(pdev, index, tag);
+ break;
+ default:
+ err = -EINVAL;
+ }
+
+ if (err) {
+ pcie_disable_tph(pdev);
+ return err;
+ }
+
+ set_ctrl_reg_req_en(pdev, pdev->tph_mode);
Just looking at this code in mainline, and I don't trust my
understanding quite enough to send a patch myself, but doesn't this want
to be pdev->tph_req_type, rather than tph_mode?
Thanks,
Robin.
+
+ pci_dbg(pdev, "set steering tag: %s table, index=%d, tag=%#04x\n",
+ (loc == PCI_TPH_LOC_MSIX) ? "MSI-X" : "ST", index, tag);
+
+ return 0;
+}
