Re: [PATCH v4 0/4] PCI: ep: dwc/imx6: Add bus address support for PCI endpoint devices

Bjorn Helgaas
2024-10-25T20:48:20Z

On Thu, Oct 24, 2024 at 04:41:42PM -0400, Frank Li wrote:
> Endpoint Root complex
> ┌───────┐ ┌─────────┐
> ┌─────┐ │ EP │ │ │ ┌─────┐
> │ │ │ Ctrl │ │ │ │ CPU │
> │ DDR │ │ │ │ ┌────┐ │ └──┬──┘
> │ │◄──────┼─ATU ◄─┼────────┼─┤BarN│◄─┼─────────┘
> │ │ │ │ │ └────┘ │ Outbound Transfer
> └─────┘ │ │ │ │
> │ │ │ │
> │ │ │ │
> │ │ │ │ Inbound Transfer
> │ │ │ │ ┌──▼──┐
> ┌───────┐ │ │ │ ┌───────┼─────►│DDR │
> │ │ outbound Transfer* │ │ │ └─────┘
> ┌─────┐ │ Bus ┼─────►│ ATU ─┬────────┼─┘ │
> │ │ │ Fabric│Bus │ │ PCI Addr │
> │ CPU ├───►│ │Addr │ │ 0xA000_0000 │
> │ │CPU │ │0x8000_0000 │ │ │
> └─────┘Addr└───────┘ │ │ │ │
> 0x7000_0000 └───────┘ └─────────┘
>
> Add `bus_addr_base` to configure the outbound window address for CPU write.
> The BUS fabric generally passes the same address to the PCIe EP controller,
> but some BUS fabrics convert the address before sending it to the PCIe EP
> controller.
>
> Above diagram, CPU write data to outbound windows address 0x7000_0000,
> Bus fabric convert it to 0x8000_0000. ATU should use BUS address
> 0x8000_0000 as input address and convert to PCI address 0xA000_0000.

The above doesn't match what's in patch 1/4, and I think the version
in 1/4 is better, so I'll comment there.

To avoid confusion, it might be better not to duplicate it in 0/4 and
1/4.

> 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 = <0x5f010000 0x00010000>,
> <0x80000000 0x10000000>;
> reg-names = "dbi", "addr_space";
> ...
> };
> ...
> };
>
> 'ranges' in bus@5f000000 descript how address convert from CPU address
> to BUS address.
>
> Use `of_property_read_reg()` to obtain the BUS address and set it to the
> ATU correctly, eliminating the need for vendor-specific cpu_addr_fixup().
>
> The 1st patch implement above method in dwc common driver.
> The 2nd patch update imx6's binding doc to add fsl,imx8q-pcie-ep.
> The 3rd patch fix a pci-mx6's a bug
> The 4th patch enable pci ep function.
>
> The imx8q's dts is usptreaming, the pcie-ep part is below.
>
> hsio_subsys: bus@5f000000 {
> compatible = "simple-bus";
> #address-cells = <1>;
> #size-cells = <1>;
> /* Only supports up to 32bits DMA, map all possible DDR as inbound ranges */
> dma-ranges = <0x80000000 0 0x80000000 0x80000000>;
> ranges = <0x5f000000 0x0 0x5f000000 0x01000000>,
> <0x80000000 0x0 0x70000000 0x10000000>;
>
> pcieb_ep: pcie-ep@5f010000 {
> compatible = "fsl,imx8q-pcie-ep";
> reg = <0x5f010000 0x00010000>,
> <0x80000000 0x10000000>;
> reg-names = "dbi", "addr_space";
> num-lanes = <1>;
> interrupts = <GIC_SPI 104 IRQ_TYPE_LEVEL_HIGH>;
> interrupt-names = "dma";
> clocks = <&pcieb_lpcg IMX_LPCG_CLK_6>,
> <&pcieb_lpcg IMX_LPCG_CLK_4>,
> <&pcieb_lpcg IMX_LPCG_CLK_5>;
> clock-names = "dbi", "mstr", "slv";
> power-domains = <&pd IMX_SC_R_PCIE_B>;
> fsl,max-link-speed = <3>;
> num-ib-windows = <6>;
> num-ob-windows = <6>;
> };
> };
>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> Changes in v4:
> - Fix 32bit build error
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202410230328.BTHareG1-lkp@intel.com/
> - Link to v3: https://lore.kernel.org/r/20241021-pcie_ep_range-v3-0-b13526eb0089@nxp.com
>
> Changes in v3:
> - Add mani' review tag for patch 3,4
> - Add varible using_dtbus_info to control use bus range information instead
> cpu_address_fixup().
> - Link to v2: https://lore.kernel.org/r/20240923-pcie_ep_range-v2-0-78d2ea434d9f@nxp.com
>
> Changes in v2:
> - Totally rewrite with difference method. 'range' should in bus node
> instead pcie-ep node because address convert happen at bus fabric. Needn't
> add 'range' property at pci-ep node.
> - Link to v1: https://lore.kernel.org/r/20240919-pcie_ep_range-v1-0-b3e9d62780b7@nxp.com
>
> ---
> Frank Li (4):
> PCI: dwc: ep: Add bus_addr_base for outbound window
> dt-bindings: PCI: fsl,imx6q-pcie-ep: Add compatible string fsl,imx8q-pcie-ep
> PCI: imx6: Pass correct sub mode when calling phy_set_mode_ext()
> PCI: imx6: Add i.MX8Q PCIe Endpoint (EP) support
>
> .../devicetree/bindings/pci/fsl,imx6q-pcie-ep.yaml | 38 +++++++++++++++++++++-
> drivers/pci/controller/dwc/pci-imx6.c | 26 ++++++++++++++-
> drivers/pci/controller/dwc/pcie-designware-ep.c | 14 +++++++-
> drivers/pci/controller/dwc/pcie-designware.h | 9 +++++
> 4 files changed, 84 insertions(+), 3 deletions(-)
> ---
> base-commit: afb15ca28055352101286046c1f9f01fdaa1ace1
> change-id: 20240918-pcie_ep_range-4c5c5e300e19
>
> Best regards,
> ---
> Frank Li <Frank.Li@nxp.com>
>