PCI/VMD: Configure MPS settings before adding devices

In order to provide the most performance and/or compatible settings,
ensure VMD root buses observe the pcie bus tuning settings by
configuring those settings prior to adding the devices to the pcie tree.

This patch open-codes pci_rescan_bus() and configures the buses prior to
adding devices and attaching drivers.

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 3890812cdf87..cf6816b55b5e 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -571,6 +571,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
         LIST_HEAD(resources);
         resource_size_t offset[2] = {0};
         resource_size_t membar2_offset = 0x2000, busn_start = 0;
+        struct pci_bus *child;
 
         /*
          * Shadow registers may exist in certain VMD device ids which allow
@@ -698,7 +699,19 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
         vmd_attach_resources(vmd);
         vmd_setup_dma_ops(vmd);
         dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
-        pci_rescan_bus(vmd->bus);
+
+        pci_scan_child_bus(vmd->bus);
+        pci_assign_unassigned_bus_resources(vmd->bus);
+
+        /*
+         * VMD root buses are virtual and don't return true on pci_is_pcie()
+         * and will fail pcie_bus_configure_settings() early. It can instead be
+         * run on each of the real root ports.
+         */
+        list_for_each_entry(child, &vmd->bus->children, node)
+                pcie_bus_configure_settings(child);
+
+        pci_bus_add_devices(vmd->bus);
 
         WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj,
                                "domain"), "Can't create symlink to domain\n");