Re: [Linaro-acpi] [PATCH V8 9/9] pci, acpi: ARM64 support for ACPI based generic PCI host controller

On Monday, May 30, 2016 5:14:22 PM CEST Tomasz Nowicki wrote:

•   bsz = 1 << pci_generic_ecam_ops.bus_shift;
  

•   cfgres.start = root->mcfg_addr + bus_res->start * bsz;
  

•   cfgres.end = cfgres.start + resource_size(bus_res) * bsz - 1;
  

•   cfgres.flags = IORESOURCE_MEM;
  

•   cfg = pci_ecam_create(&root->device->dev, &cfgres, bus_res,
  

•                         &pci_generic_ecam_ops);
  

•   if (IS_ERR(cfg)) {
  

•           pr_err("%04x:%pR error %ld mapping CAM\n", seg, bus_res,
  

•                  PTR_ERR(cfg));
  

•           return PTR_ERR(cfg);
  

•   }
  

•   ri->cfg = cfg;
  

•   return 0;
  

+}

I wonder if we could do this a little simpler and just put a pointer to the mmconfig space into struct pci_host_bridge, and then have a trivial map_bus function alongside pci_generic_config_read/pci_generic_config_write.

As this code is specific to arch/arm64, we don't need any of the complexity of drivers/pci/ecam.c, which basically only exists to work around the limited virtual address space of 32-bit machines.

Arnd