On 17/02/2017 15:38, Bjorn Helgaas wrote: > On Fri, Feb 17, 2017 at 10:20:20AM +0100, Mason wrote: > >> There might be some kind of misunderstanding. >> >> I don't plan to write a driver for a device that plugs into a PCIe slot. >> >> I intend to write a driver for the PCIe controller itself, which is >> embedded in the SoC. (In order to support different types of PCIe >> devices, with their respective drivers already upstream.) >> >> I think the controller driver belongs in drivers/pci/host ? > > Sorry, I indeed misunderstood you. > > The native PCI host controller drivers indeed live in > drivers/pci/host/. > > I don't know anything about your hardware or environment, but I highly > encourage you to use ACPI (drivers/acpi/pci_root.c, with a little bit > of arch support) or generic DT (drivers/pci/host/pci-host-generic.c) > instead of writing a custom host controller driver. > > The native drivers in drivers/pci/host are a huge maintenance hassle > for no real benefit. My SoC is built around an ARM Cortex A9. I don't think (?) this platform has any support for ACPI. I'm currently using this DT description: http://lxr.free-electrons.com/source/arch/arm/boot/dts/tango4-common.dtsi The "legacy" driver sits at ~700 lines. It would be awesome to be able to discard all of it, and rely on generic upstream code. But I don't understand how it is possible for a generic driver to support whatever crazy solution some random vendor has come up with? Regards.
