On Thu, Jan 30, 2025 at 11:02:06AM -0500, Frank Li wrote: > On Wed, Jan 29, 2025 at 05:23:50PM -0600, Bjorn Helgaas wrote: > > On Tue, Jan 28, 2025 at 05:07:35PM -0500, Frank Li wrote: > > > Rename `cpu_addr` to `parent_bus_addr` in the DesignWare ATU configuration. > > > The ATU translates parent bus addresses to PCI addresses, which are often > > > the same as CPU addresses but can differ in systems where the bus fabric > > > translates addresses before passing them to the PCIe controller. This > > > renaming clarifies the purpose and avoids confusion. > > > > Based on dw_pcie_ep_inbound_atu() below, I guess the ATU can also > > translate PCI addresses from incoming DMA to parent bus addresses? > > Yes, but root complex don't use it. Only EP use it. because most PCI root > complex system doesn't transfer incoming address, which generally use iommu > to do that. Linux already allow a simple map by use dt's dma-ranges and dma > API already handle it. > > previous 'cpu_addr' is actually 'dma_bus_addr'. > > > > > It's worth noting here that this patch only renames the member, and > > IIUC, parent_bus_addr still incorrectly contains CPU physical > > addresses. > > Anyway, call 'cpu_addr' for dw_pcie_ep_inbound_atu is wrong. Only one place > call dw_pcie_ep_inbound_atu(), that's dw_pcie_ep_set_bar(), which use > epf_bar->phys_addr, I think name 'phys_addr' is okay because most case it > is refer to dma address space. Bjoin: Do you any concern/comments about my reply? how to move forward? keep old cpu_addr or rename to parent_bus_addr, or futher work need be done. Frank > > Frank > > > > > +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c > > > @@ -128,7 +128,7 @@ static int dw_pcie_ep_write_header(struct pci_epc *epc, u8 func_no, u8 vfunc_no, > > > } > > > > > > static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, u8 func_no, int type, > > > - dma_addr_t cpu_addr, enum pci_barno bar, > > > + dma_addr_t parent_bus_addr, enum pci_barno bar, > > > size_t size)
