On Wed, Dec 4, 2013 at 11:30 PM, Jagan Teki <jagannadh.teki@xxxxxxxxx> wrote: > 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 Why did you keep the pci_bus_add_device() label? There are no calls from arch code. The only calls from outside the PCI core are from i82875p_setup_overfl_dev(), asus_rfkill_hotplug(), and eeepc_rfkill_hotplug(). These are all hacks that should not be emulated. 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
