On 2025/5/7 15:38, Niklas Cassel wrote:

On Wed, May 07, 2025 at 01:34:37AM +0800, Hans Zhang wrote:

(snip)

quoted

  static void pci_configure_mps(struct pci_dev *dev)
  {
  	struct pci_dev *bridge = pci_upstream_bridge(dev);

@@ -2178,6 +2209,10 @@ static void pci_configure_mps(struct pci_dev *dev)
  		return;
  	}

We should probably add a comment explaining why we are doing this here.

Perhaps something like:

/*
  * Unless MPS strategy is PCIE_BUS_TUNE_OFF (don't touch MPS at all),
  * start off by setting root ports' MPS to MPSS. Depending on the MPS
  * strategy, and the MPSS of the devices below the root port, the MPS
  * of the root port might get overriden later.
  */

Dear Niklas,

Thank you very much for your reply and suggestions.
It will be added in the next version.

Best regards,
Hans

quoted

+	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT &&
+	    pcie_bus_config != PCIE_BUS_TUNE_OFF)
+		pcie_write_mps(dev, 128 << dev->pcie_mpss);
+
  	if (!bridge || !pci_is_pcie(bridge))
  		return;
  

Kind regards,
Niklas