Messages in this thread | | | Date | Mon, 27 Feb 2017 16:04:59 -0800 (PST) | From | matthew.gerlach@linux ... | Subject | Re: [RFC 7/8] fpga-region: add sysfs interface |
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On Mon, 27 Feb 2017, Moritz Fischer wrote:
> Alan, > > On Mon, Feb 27, 2017 at 12:09 PM, Alan Tull <delicious.quinoa@gmail.com> wrote: > > >> First case: embedded FPGA. The hardware has one FPGA. The image is >> designed for a specific board, so there's no problem including the >> enumeration in the image. > > Agreed. > >> Second case: embedded FPGA + a PCIe FPGA. The image will be specific >> as to whether it goes into the embedded FPGA or the PCIe one. > > Agreed. > > >> Third case: multiple PCIe FPGAs. The enumeration base will be the >> PCIe bus of the individual FPGA. If the FPGAs don't have unique pin >> connections, then the images could go on any of the PCie FPGAs. If >> there are unique pin connections, then the image will be specific to >> the FPGA and having the enumeration data in the image is that much >> more helpful for keeping things straight. Part of the header could >> specify which specific FPGA it should go on if it is restricted. > > Agreed. > >> Of course if the FPGAs have > 1 PR regions, most FPGA architectures do >> not have relocatable images so those images will be specific for the >> PR region but not specific to the FPGA except as otherwise noted >> above. >> >> So again, including enumeration data in the bitstream should work >> unless I'm missing something. What am I missing here? > > If you enumeration base is sufficiently smart, I suppose that can work. > What you'd probably want is some sort of extension to the platform bus?
I think there is merit it considering the platform bus as part of the overal enumeration strategy. When using device trees, the platform bus is involved. I have also seen other folks enumerate over a platform bus based on data in a format other than device tree. I have experimented with instantiating platform devices from my pcie driver, but I didn't completely work, which could be related to using a fairly old 3.10 kernel.
Matthew Gerlach
> > I really need to take another look at how non-dt systems enumerate to > give better feedback on this. > > Cheers, > > Moritz > -- > To unsubscribe from this list: send the line "unsubscribe linux-fpga" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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