On 2015/5/26 16:09, Arnd Bergmann wrote: > On Monday 25 May 2015 14:10:37 Jingoo Han wrote: >> 'pp->root_bus_nr' is initialized as '-1' at some soc-specific drivers >> However, 'sys->busnr' is set as '0, 1, 2 ...' by pcibios_init_hw() >> in arch/arm/kernel/bios32.c. '0, 1, 2 ...' means the number of >> each host controller. >> >> So, without setting 'pp->root_bus_nr' as '0, 1, 2, ...', >> it makes the problem. >> >> Thus, we need to come up with the way to resolve this. >> >> 1. Setting 'pp->root_bus_nr' as '0, 1, 2 ..' by each soc-specific driver. >> >> e.g) >> >> ./drivers/pci/host/pci-exynos.c >> @@ -534,7 +534,7 @@ static int __init exynos_add_pcie_port(struct pcie_port *pp, >> } >> } >> >> - pp->root_bus_nr = -1; >> + pp->root_bus_nr++; >> pp->ops = &exynos_pcie_host_ops; >> >> ./drivers/pci/host/pci-imx6.c >> @@ -541,7 +541,7 @@ static int __init imx6_add_pcie_port(struct pcie_port *pp, >> } >> } >> >> - pp->root_bus_nr = -1; >> + pp->root_bus_nr++; >> pp->ops = &imx6_pcie_host_ops; >> >> ./drivers/pci/host/pci-keystone.c >> @@ -312,7 +312,7 @@ static int __init ks_add_pcie_port(struct keystone_pcie *ks_pcie, >> return ret; >> } >> >> - pp->root_bus_nr = -1; >> + pp->root_bus_nr++; >> pp->ops = &keystone_pcie_host_ops; >> >> ./drivers/pci/host/pci-layerscape.c >> @@ -101,7 +101,7 @@ static int ls_add_pcie_port(struct ls_pcie *pcie) >> pp = &pcie->pp; >> pp->dev = pcie->dev; >> pp->dbi_base = pcie->dbi; >> - pp->root_bus_nr = -1; >> + pp->root_bus_nr++; >> pp->ops = &ls_pcie_host_ops; >> >> ./drivers/pci/host/pcie-spear13xx.c >> @@ -287,7 +287,7 @@ static int spear13xx_add_pcie_port(struct pcie_port *pp, >> return ret; >> } >> >> - pp->root_bus_nr = -1; >> + pp->root_bus_nr++; >> pp->ops = &spear13xx_pcie_host_ops; >> >> >> 2. Setting 'pp->root_bus_nr' as '0, 1, 2 ..' by pcie-designware.c >> >> I believe that someone will give better idea. > > Assigning the root bus number through hw_pci is a historic artifact > from drivers that probe multiple host bridges at the same time. > Some legacy ARM platforms still do that (specifically all the ones > that set nr_controllers to >1: dove, mv78xx0, orion5x, and iop), > but all modern platforms should probe each host bridge separately, > either from a platform driver probe function, or they only have > one and hardcode that fact in the ARM platform code. > > For the drivers in drivers/pci/host, we give each host controller > its own PCI domain, which means we can have overlapping bus numbers > and do not need the heuristic to split the available 255 bus numbers > across the present host bridges. > > Arnd Hi Arnd, Thanks for your explanation about this. Best Regards, Zhou > > . > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
