On Tue, Dec 3, 2013 at 11:20 PM, Jagan Teki <jagannadh.teki@xxxxxxxxx> wrote: > Thanks for your quick response. > Please find my comments below. > > On Tue, Dec 3, 2013 at 11:09 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: >> On Tue, Dec 3, 2013 at 4:24 AM, Jagan Teki <jagannadh.teki@xxxxxxxxx> wrote: >>> Hi, >>> >>> I have few question on Linux PCIe subsystem, I am trying to understand >>> the PCIe on ARM platform. >>> 1. Compared to PCI, PCIe have an extra port functionalists/services >>> which is implemented drivers/pci/pcie/* is it true? >> >> Yes. >> >>> 2. PCIe root complex is same as Host controller drivers in linux drivers/host/* >> >> Yes. >> >>> 3. As individual endpoint drivers are registered to pci_core as >>> pci_driver_register, then what is the common call for registering >>> individual HC driver to pci-core? >> >> The host controller-PCI core interface is not as mature as the >> pci_register_driver() interface. The basic interface is >> pci_scan_root_bus(). If you skim through the drivers in >> drivers/pci/host/* and drivers/acpi/pci_root.c, the interface to the >> PCI core will be fairly obvious. And you'll learn what the existing >> practices are in case you need to add or modify something. > > OK. > > I understand the flow as below - please correct if am wrong. > > From low level (hw) - HC driver has a platform registration using > platform_driver_register() to lower layer > and then pci_scan_root_bus() --> pci_common_init_dev() registration to > upper layer as PCI - BIOS and then ends. Yes. Sometime HC drivers use platform_driver_register(); other use something else depending on how the HC device is enumerated. For example, drivers/acpi/pci_root.c uses something else to deal with host bridges in the ACPI namespace. > From upper level (app) - each endpoint driver has > pci_driver_register() call to PCI Core for lower level Yes. > and then the upper level registration is based on endpoint(). I don't know what you mean here (I don't know of a function named "endpoint()"). But the driver model matches drivers to PCI functions based on vendor and device IDs. A Linux "pci_dev" is what the PCI specs refer to as a "function." > What is the connection here for PCI-BIOS and PCI-Core here, does these > are two different entities means there is no common call for these? > I see for ARM - "arch/arm/kernel/bios32.c" is PCI-BIOS is it correct? > does we have separate BIOS codes for architectures? The "pcibios_*" functions are architecture-specific things called by the generic PCI core. Generally, things specified by the PCI specs are architecture-independent and should be in the PCI core (drivers/pci/*). Bjorn -- 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
