Re: [PATCH v7 2/7] PCI: dwc: Using parent_bus_addr in of_range to eliminate cpu_addr_fixup()

Manivannan Sadhasivam
2024-11-15T17:53:12Z

On Tue, Oct 29, 2024 at 12:36:35PM -0400, Frank Li wrote:

Please reword the subject as:

PCI: dwc: Use devicetree 'ranges' property to get rid of cpu_addr_fixup() callback

> parent_bus_addr in struct of_range 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:
>
> ┌─────────┐ ┌────────────┐
> ┌─────┐ │ │ IA: 0x8ff8_0000 │ │
> │ CPU ├───►│ ┌────►├─────────────────┐ │ PCI │
> └─────┘ │ │ │ IA: 0x8ff0_0000 │ │ │
> CPU Addr │ │ ┌─►├─────────────┐ │ │ Controller │
> 0x7ff8_0000─┼───┘ │ │ │ │ │ │
> │ │ │ │ │ │ │ PCI Addr
> 0x7ff0_0000─┼──────┘ │ │ └──► IOSpace ─┼────────────►
> │ │ │ │ │ 0
> 0x7000_0000─┼────────►├─────────┐ │ │ │
> └─────────┘ │ └──────► CfgSpace ─┼────────────►
> BUS Fabric │ │ │ 0
> │ │ │
> └──────────► MemSpace ─┼────────────►
> IA: 0x8000_0000 │ │ 0x8000_0000
> └────────────┘
>
> bus@5f000000 {
> compatible = "simple-bus";
> #address-cells = <1>;
> #size-cells = <1>;
> ranges = <0x80000000 0x0 0x70000000 0x10000000>;
>
> pcie@5f010000 {
> compatible = "fsl,imx8q-pcie";
> reg = <0x5f010000 0x10000>, <0x8ff00000 0x80000>;
> reg-names = "dbi", "config";
> #address-cells = <3>;
> #size-cells = <2>;
> device_type = "pci";
> bus-range = <0x00 0xff>;
> ranges = <0x81000000 0 0x00000000 0x8ff80000 0 0x00010000>,
> <0x82000000 0 0x80000000 0x80000000 0 0x0ff00000>;
> ...
> };
> };
>
> Term internal address (IA) here means the address just before PCIe
> controller. After ATU use this IA instead CPU address, cpu_addr_fixup() can
> be removed.
>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> Add a resource_size_t parent_bus_addr local varible to fix 32bit build
> error.
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202410291546.kvgEWJv7-lkp@intel.com/
>
> Chagne from v5 to v6
> -add comments for of_property_read_reg().
>
> Change from v4 to v5
> - remove confused 0x5f00_0000 range in sample dts.
> - reorder address at above diagram.
>
> Change from v3 to v4
> - none
>
> Change from v2 to v3
> - %s/cpu_untranslate_addr/parent_bus_addr/g
> - update diagram.
> - improve commit message.
>
> Change from v1 to v2
> - update because patch1 change get untranslate address method.
> - add using_dtbus_info in case break back compatibility for exited platform.
> ---
> drivers/pci/controller/dwc/pcie-designware-host.c | 55 ++++++++++++++++++++++-
> drivers/pci/controller/dwc/pcie-designware.h | 8 ++++
> 2 files changed, 62 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 3e41865c72904..ea01b7bda0a76 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -418,6 +418,34 @@ static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp)
> }
> }
>
> +static int dw_pcie_get_untranslate_addr(struct dw_pcie *pci, resource_size_t pci_addr,
> + resource_size_t *i_addr)

dw_pcie_get_parent_addr()? Since this function is anyway reading the parent
address from DT.

> +{
> + struct device *dev = pci->dev;
> + struct device_node *np = dev->of_node;
> + struct of_range_parser parser;
> + struct of_range range;
> + int ret;
> +
> + if (!pci->using_dtbus_info) {
> + *i_addr = pci_addr;
> + return 0;
> + }
> +
> + ret = of_range_parser_init(&parser, np);
> + if (ret)
> + return ret;
> +
> + for_each_of_pci_range(&parser, &range) {
> + if (pci_addr == range.bus_addr) {
> + *i_addr = range.parent_bus_addr;
> + break;
> + }
> + }
> +
> + return 0;
> +}
> +
> int dw_pcie_host_init(struct dw_pcie_rp *pp)
> {
> struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> @@ -427,6 +455,7 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
> struct resource_entry *win;
> struct pci_host_bridge *bridge;
> struct resource *res;
> + int index;
> int ret;
>
> raw_spin_lock_init(&pp->lock);
> @@ -440,6 +469,20 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
> pp->cfg0_size = resource_size(res);
> pp->cfg0_base = res->start;
>
> + if (pci->using_dtbus_info) {
> + index = of_property_match_string(np, "reg-names", "config");
> + if (index < 0)
> + return -EINVAL;
> + /*
> + * Retrieve the parent bus address of PCI config space.
> + * If the parent bus ranges in the device tree provide
> + * the correct address conversion information, set
> + * 'using_dtbus_info' to true, The 'cpu_addr_fixup()'
> + * can be eliminated.
> + */

Nobody will switch to 'ranges' property if you mention it in comments. We
usually add dev_warn_once() to print a warning for broken DT so that the users
will try to fix it. You can use below diff (as a separate patch ofc):

```
diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 6d6cbc8b5b2c..d1e5395386fe 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -844,6 +844,9 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci)
dw_pcie_cap_is(pci, IATU_UNROLL) ? "T" : "F",
pci->num_ob_windows, pci->num_ib_windows,
pci->region_align / SZ_1K, (pci->region_limit + 1) / SZ_1G);
+
+ if (pci->ops && pci->ops->cpu_addr_fixup)
+ dev_warn_once(pci->dev, "Broken \"ranges\" property detected. Please fix DT!\n");
}

static u32 dw_pcie_readl_dma(struct dw_pcie *pci, u32 reg)
```

> + of_property_read_reg(np, index, &pp->cfg0_base, NULL);

Can you explain what is going on here?

> + }
> +
> pp->va_cfg0_base = devm_pci_remap_cfg_resource(dev, res);
> if (IS_ERR(pp->va_cfg0_base))
> return PTR_ERR(pp->va_cfg0_base);
> @@ -462,6 +505,9 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
> pp->io_base = pci_pio_to_address(win->res->start);
> }
>
> + if (dw_pcie_get_untranslate_addr(pci, pp->io_bus_addr, &pp->io_base))
> + return -ENODEV;

Use actual return value here and below.

> +
> /* Set default bus ops */
> bridge->ops = &dw_pcie_ops;
> bridge->child_ops = &dw_child_pcie_ops;
> @@ -722,6 +768,8 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
>
> i = 0;
> resource_list_for_each_entry(entry, &pp->bridge->windows) {
> + resource_size_t parent_bus_addr;
> +
> if (resource_type(entry->res) != IORESOURCE_MEM)
> continue;
>
> @@ -730,9 +778,14 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
>
> atu.index = i;
> atu.type = PCIE_ATU_TYPE_MEM;
> - atu.cpu_addr = entry->res->start;
> + parent_bus_addr = entry->res->start;
> atu.pci_addr = entry->res->start - entry->offset;
>
> + if (dw_pcie_get_untranslate_addr(pci, entry->res->start, &parent_bus_addr))
> + return -EINVAL;
> +
> + atu.cpu_addr = parent_bus_addr;
> +
> /* Adjust iATU size if MSG TLP region was allocated before */
> if (pp->msg_res && pp->msg_res->parent == entry->res)
> atu.size = resource_size(entry->res) -
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 347ab74ac35aa..f8067393ad35a 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -463,6 +463,14 @@ struct dw_pcie {
> struct reset_control_bulk_data core_rsts[DW_PCIE_NUM_CORE_RSTS];
> struct gpio_desc *pe_rst;
> bool suspended;
> + /*
> + * Use device tree 'ranges' property of bus node instead using
> + * cpu_addr_fixup(). Some old platform dts 'ranges' in bus node may not
> + * reflect real hardware's behavior. In case break these platform back
> + * compatibility, add below flags. Set it true if dts already correct
> + * indicate bus fabric address convert.

/*
* This flag indicates that the vendor driver uses devicetree 'ranges'
* property to allow iATU to use the Intermediate Address (IA) for
* outbound mapping. Using this flag also avoids the usage of
* 'cpu_addr_fixup' callback implementation in the driver.
*/

> + */
> + bool using_dtbus_info;

'use_dt_ranges'?

- Mani

--
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