On Wed, Dec 4, 2013 at 11:35 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: > On Wed, Dec 4, 2013 at 10:00 AM, Jagan Teki <jagannadh.teki@xxxxxxxxx> wrote: >> On Wed, Dec 4, 2013 at 8:41 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: >>> 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." >> Sorry it's typo - added () >> >>> >>>> 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/*). >> >> I have some good information to discuss from this thread. >> Can you please verify this Linux PCIe subsystem stack - comment >> whether my understanding is correct/not. >> (I just draw this based on driver calls flow - to accommodate with in >> the Linux cores) >> http://jagannadhteki.blog.com/2013/12/04/linux-pcie-subsystem/ > > Yes, that makes sense. I wouldn't label the PCIBIOS - PCI core link > as "pci_bus_add_device()"; pci_bus_add_device() is part of the PCI > core's generic enumeration code and shouldn't be called by > arch-specific code. The link going from PCI core to PCIBIOS is the > set of "pcibios_*()" functions. Going from PCIBIOS to the PCI core, > it's mostly just pci_scan_root_bus(). Yes - understand your point. I made few changes accordingly. http://jagannadhteki.blog.com/files/2013/12/Linux_PCIe_zynq.png I am planning to document this subsystem into Documentation/PCI/* with brief description of important blocks, any comments? > I also probably wouldn't put in links between VFS and AER, HP, PME, > and VC. It's true that there are some sysfs files that influence the > operation of those PCIe features, but mostly for debugging and > administration. They aren't something useful to ordinary user > programs. -- Thanks, Jagan. -------- Jagannadha Sutradharudu Teki, E: jagannadh.teki@xxxxxxxxx, P: +91-9676773388 Engineer - System Software Hacker U-boot - SPI Custodian and Zynq APSOC Ln: http://www.linkedin.com/in/jaganteki -- 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
