Re: [RFC PATCH V2 1/3] PCI: hisi: re-architect Hip05/Hip06 controllers driver to preapare for ACPI

Arnd Bergmann
2016-09-01T14:02:59Z

On Thursday, September 1, 2016 8:44:49 PM CEST Dongdong Liu wrote:
> 在 2016/9/1 15:41, Arnd Bergmann 写道:
> > On Thursday, September 1, 2016 10:05:29 AM CEST Dongdong Liu wrote:
> >> 在 2016/8/31 19:45, Arnd Bergmann 写道:
> >>> On Wednesday, August 31, 2016 7:48:12 PM CEST Dongdong Liu wrote:
> I know your point.
>
> 1. For our host bridge , ".map_bus = pci_ecam_map_bus" is only suitable for
> accessing the EP config space.
> pci_generic_config_read32() need to call "addr = bus->ops->map_bus(bus, devfn, where & ~0x3);",
>
> drivers/pci/host/pcie-hisi-acpi.c
> static struct pci_ops hisi_pcie_ops = {
> .map_bus = pci_ecam_map_bus,
> .read = hisi_pcie_acpi_rd_conf,
> .write = hisi_pcie_acpi_wr_conf,
> };
>
> Yes, we can change ".map_bus = pci_ecam_map_bus" to ".map_bus = hisi_pci_map_bus", and implentment hisi_pci_map_bus as below,
> then we will not need to call hisi_pcie_common_cfg_read().
>
> void __iomem *hisi_pci_map_bus(struct pci_bus *bus, unsigned int devfn, int where)
> {
> struct pci_config_window *cfg = bus->sysdata;
> void __iomem *reg_base = cfg->priv;
>
> /* for RC config access*/
> if (bus->number == cfg->busr.start)
> return reg_base + (where & ~0x3);
> else
> /* for EP config access */
> return pci_ecam_map_bus(bus, devfn, where);
> }
>
> and hisi_pcie_acpi_rd_conf() need to change as below.
> static int hisi_pcie_acpi_rd_conf(struct pci_bus *bus, u32 devfn, int where,
> int size, u32 *val)
> {
> struct pci_config_window *cfg = bus->sysdata;
>
> if (hisi_pcie_acpi_valid_config(cfg, bus, PCI_SLOT(devfn)) == 0)
> return PCIBIOS_DEVICE_NOT_FOUND;
>
> /* access RC config space */
> if (bus->number == cfg->busr.start)
> return pci_generic_config_read32(bus, devfn, where, size, val);
>
> /* access EP config space */
> return pci_generic_config_read(bus, devfn, where, size, val);
> }

Right, this is what I had in mind.

> 2. We need to backward compatible with the old dt way config access as below code,
> so we have to call hisi_pcie_common_cfg_read() when accessing the RC config space.
> For this, we have to call hisi_pcie_common_cfg_read().
>
> drivers/pci/host/pcie-hisi.c
> static inline int hisi_pcie_cfg_read(struct pcie_port *pp, int where,
> int size, u32 *val)
> {
> struct hisi_pcie *pcie = to_hisi_pcie(pp);
>
> return hisi_pcie_common_cfg_read(pcie->reg_base, where, size, val);
> }
>
> static struct pcie_host_ops hisi_pcie_host_ops = {
> .rd_own_conf = hisi_pcie_cfg_read,
> .wr_own_conf = hisi_pcie_cfg_write,
> .link_up = hisi_pcie_link_up,
> };

I think this would be easier if you separate the ACPI code from the
DT code and not try to have a common file used for both.

Sharing the config space accessors really isn't worth it when both
variants are fairly simple to do, but they don't fit in a common
model because one is called from the ACPI quirks and the other
is called from the dw-pcie driver with completely different calling
conventions.

ARnd