On Wed, Mar 12, 2025 at 04:37:57PM -0500, Bjorn Helgaas wrote:
> On Mon, Mar 10, 2025 at 04:16:43PM -0400, Frank Li wrote:
> > parent_bus_offset in resource_entry can indicate address information just
> > ahead of PCIe controller. Most system's bus fabric use 1:1 map between
> > input and output address. but some hardware like i.MX8QXP doesn't use 1:1
> > map. See below diagram:
>
> > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > @@ -478,6 +478,15 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
> > bridge->ops = &dw_pcie_ops;
> > bridge->child_ops = &dw_child_pcie_ops;
> >
> > + /*
> > + * visconti_pcie_cpu_addr_fixup() use pp->io_base,
> > + * so have to call dw_pcie_init_parent_bus_offset() after init
> > + * pp->io_base.
> > + */
> > + ret = dw_pcie_init_parent_bus_offset(pci, "config", pp->cfg0_base);
> > + if (ret)
> > + return ret;
>
> The ordering in dw_pcie_host_init() doesn't look right to me. We have
> this:
>
> dw_pcie_host_init
> dw_pcie_get_resources
> dw_pcie_cfg0_setup
> devm_pci_alloc_host_bridge
> win = resource_list_first_type(&bridge->windows, IORESOURCE_IO)
> pp->io_base = pci_pio_to_address(win->res->start)
> bridge->ops = ...
> bridge->child_ops = ...
> dw_pcie_init_parent_bus_offset
> pp->ops->init
>
> devm_pci_alloc_host_bridge() is generic, so it obviously can't depend
> on any dwc-specific things. I think the ordering should be more like
> this:
>
> dw_pcie_host_init
> devm_pci_alloc_host_bridge # generic
> dw_pcie_get_resources # dwc RP and EP
>
> dw_pcie_cfg0_setup
> win = resource_list_first_type(&bridge->windows, IORESOURCE_IO)
> pp->io_base = pci_pio_to_address(win->res->start)
> dw_pcie_init_parent_bus_offset
>
> bridge->ops = ...
> bridge->child_ops = ...
> pp->ops->init
>
> and everything in the second block (dw_pcie_cfg0_setup() through
> dw_pcie_init_parent_bus_offset()) is strictly DT-related resource
> setup and could all go in a dw_pcie_host_get_resources() or similar.
It is not related with these patch series. I can change it if you like.
Frank
>
> > if (pp->ops->init) {
> > ret = pp->ops->init(pp);
> > if (ret)
> >
> > --
> > 2.34.1
> >
