Re: [PATCH v19 2/2] PCI: Add a quirk for AMD PCIe root ports w/ USB4 controllers

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On 9/15/2023 02:08, Lukas Wunner wrote:
On Thu, Sep 14, 2023 at 09:33:54PM -0500, Mario Limonciello wrote:
+static bool child_has_amd_usb4(struct pci_dev *pdev)
+	struct pci_dev *child = NULL;
+	while ((child = pci_get_class(PCI_CLASS_SERIAL_USB_USB4, child))) {
+		if (child->vendor != PCI_VENDOR_ID_AMD)
+			continue;
+		if (pcie_find_root_port(child) != pdev)
+			continue;
+		return true;
+	}
+	return false;

What's the purpose of the pcie_find_root_port() check?  PCI is a hierarchy,
not a graph, so a device cannot have any other Root Port but the one below
which you're searching.

If the purpose is to check that the port is a Root Port (if the PCI IDs
you're using in the DECLARE_PCI_FIXUP_* clauses match non-Root Ports),
check for pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT.  (No need to
check for that in every loop iteration obviously, just check once in
the fixup.)



The reason to look for it the way that I did was that there are multiple root ports with the exact same PCI ID.

The problem only occurs on the root port that happens to have an AMD USB4 controller connected.

[Index of Archives]     [DMA Engine]     [Linux Coverity]     [Linux USB]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Greybus]

  Powered by Linux