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SubjectRe: Need help on Linux PCIe
Thanks for your quick response.
Please find my comments below.

On Tue, Dec 3, 2013 at 11:09 PM, Bjorn Helgaas <> wrote:
> On Tue, Dec 3, 2013 at 4:24 AM, Jagan Teki <> 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.


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.

From upper level (app) - each endpoint driver has
pci_driver_register() call to PCI Core for lower level and then the
level registration is based on endpoint().

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?

Jagannadha Sutradharudu Teki,
E:, P: +91-9676773388
Engineer - System Software Hacker
U-boot - SPI Custodian and Zynq APSOC

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