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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250116_144905_136379_61C367B0 X-CRM114-Status: GOOD ( 29.35 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jan 16, 2025 at 03:02:44PM -0500, Frank Li wrote: > On Thu, Jan 16, 2025 at 01:45:58PM -0600, Bjorn Helgaas wrote: > > On Thu, Jan 16, 2025 at 01:04:16PM -0500, Frank Li wrote: > > > On Thu, Jan 16, 2025 at 09:32:39AM -0600, Bjorn Helgaas wrote: > > > > On Tue, Nov 19, 2024 at 02:44:21PM -0500, Frank Li wrote: > > > > > Endpoint > > > > > ┌───────────────────────────────────────────────┐ > > > > > │ pcie-ep@5f010000 │ > > > > > │ ┌────────────────┐│ > > > > > │ │ Endpoint ││ > > > > > │ │ PCIe ││ > > > > > │ │ Controller ││ > > > > > │ bus@5f000000 │ ││ > > > > > │ ┌──────────┐ │ ││ > > > > > │ │ │ Outbound Transfer ││ > > > > > │┌─────┐ │ Bus ┼─────►│ ATU ──────────┬┬─────► > > > > > ││ │ │ Fabric │Bus │ ││PCI Addr > > > > > ││ CPU ├───►│ │Addr │ ││0xA000_0000 > > > > > ││ │CPU │ │0x8000_0000 ││ > > > > > │└─────┘Addr└──────────┘ │ ││ > > > > > │ 0x7000_0000 └────────────────┘│ > > > > > └───────────────────────────────────────────────┘ > > > > > > > > > > Use 'ranges' property in DT to configure the iATU outbound window address. > > > > > The bus fabric generally passes the same address to the PCIe EP controller, > > > > > but some bus fabrics map the address before sending it to the PCIe EP > > > > > controller. > > > > > > > > > > Above diagram, CPU write data to outbound windows address 0x7000_0000, Bus > > > > > fabric map it to 0x8000_0000. ATU should use bus address 0x8000_0000 as > > > > > input address and map to PCI address 0xA000_0000. > > > > > > > > > > Previously, 'cpu_addr_fixup()' was used to handle address conversion. Now, > > > > > the device tree provides this information, preferring a common method. > > > > > > > > > > bus@5f000000 { > > > > > compatible = "simple-bus"; > > > > > ranges = <0x80000000 0x0 0x70000000 0x10000000>; > > > > > > > > > > pcie-ep@5f010000 { > > > > > reg = <0x80000000 0x10000000>; > > > > > reg-names ="addr_space"; > > > > > ... > > > > > }; > > > > > ... > > > > > }; > > > > > > > > > > 'ranges' in bus@5f000000 descript how address map from CPU address to bus > > > > > address. > > > > > > > > Shouldn't there also be a pcie-ep@5f010000 'ranges' property to > > > > describe the translation for the window from bus addr 0x8000_0000 to > > > > PCI addr 0xA000_0000? > > > > > > Needn't 'ranges' under pcie-ep@5f010000 because history reason. DWC use > > > reg-names "addr_space" descript outbound windows space. > > > > If reg-name "addr_space" is used instead of 'ranges' for some > > historical reason, we should mention that in the commit log so people > > don't assume that this difference is the way it's *supposed* to be > > done. > > How about add comments after > > reg-names ="addr_space"; // Indicate EP outbound windows space instead use > ranges by histortical reason. OK, that seems reasonable. Where does the 0xA000_0000 PCI address come from? I assume that's in DT somewhere too? Is there a binding in the tree that would take advantage of this patch that I can look at? arch/arm64/boot/dts/freescale/imx8-ss-hsio.dtsi has bus@5f000000 that does this translation, but I don't see any endpoint mode that uses it. > > > All regs need call of_property_read_reg() to get untranslated address. > > > ranges: use "parent_bus_addr" in [1]. > > > > I think we should at least use the same name ("parent_bus_addr", not > > "bus_addr_base") and probably also figure out a wrapper or similar way > > to use 'ranges' for future endpoint drivers and fall back to > > "addr_space" for DWC. > > Okay for name parent_bus_addr. > Do you need me to respin it? Or you change it by yourself? I can do that. Bjorn > > > > [1] https://lore.kernel.org/r/20241119-pci_fixup_addr-v8-1-c4bfa5193288@nxp.com