On 08/14/2018 11:35 AM, Bin Meng wrote: [...] >>>>>> I think knowing where Linux does this >>>>>> would be instructive to figure out where we need to have some additional >>>>>> logic added OR we can make some cost/benefit analysis to see if it makes >>>>>> more sense overall to add compatibles to some nodes rather than add to >>>>>> the binary size. >>>>> >>>>> Adding compatible does not make any sense, the PCI ID provides that >>>>> information. Adding compatible would only add redundancy which could >>>>> possibly be even harmful (ie. if the controller got replaced with >>>>> another one). >>>> >>>> To try and move things along rather than re-argue the same point, you're >>>> saying that our pci_find_and_bind_driver() is the rough equivalent of >>>> of_pci_find_child_device() or at least pci_set_of_node() (which calls >>>> of_pci_find_child_device()). >>>> >>>> So, Bin, if this isn't the right place to start down this path, where >>>> would be? Given that Linux can take a DTB and PCI bus with devices and >>>> get things right, what would it look like for U-Boot to replicate the >>>> same behavior? Instead of having to add explicit compatible nodes for >>>> each PCI device, as I understand (but correct me if I'm wrong) we're >>>> doing today. Thanks! >>> >>> So is this a requirement for all U-Boot driver subsystems to replicate >>> the same Linux behavior? If yes, can we have it officially documented >>> somewhere? >> >> No, because we are not replicating Linux behavior. >> > > But you kept mentioning you wanted U-Boot to use exactly the same DT > from Linux. And I pointed out that FreeBSD's DT files are not the same > as Linux. Here you are saying you don't want U-Boot to replicate Linux > behavior, if not the Linux behavior, what do you want to suggest then?
Just parse the information out of the DT fully and be done with it. That is what I suggest. >>> Since Marek refused to take the original U-Boot option 1 to support >>> his case, and asked U-Boot to follow Linux's practice on PCI device >>> binding, if we go that way, here is what we can do: >> >> You are inserting words into my mouth and I dislike that. I never said >> anything about Linux. I said DT is OS agnostic and U-Boot should be able >> to parse DT as fully as possible. > > See above comment. I might have used some words that made you feel > uncomfortable, and for me I felt the same way. Part of the reason is > that I am not a native English speaker and I may mis-use/interpret > words. If that's the case I apologize. Anyway I won't quarrel against > this over and over again. This does not help to move things forward. This is a technical discussion, we should use arguments, not feelings. I am fine, but thanks for your concern. >>> * Keep pci-uclass driver's post_bind() and child_post_bind() only for >>> Sandbox configuration >>> * Keep the call to pci_bus_find_devfn() in pci_bind_bus_devices() only >>> for Sandbox configuration >>> * Sandbox is special. We should limit the mechanism of matching PCI >>> emulation device via "compatible" to sandbox only >> >> I don't think this is limited to sandbox, although I don't see a >> real-world usecase right now. >> > > You are welcome to send patches against sandbox PCI codes to remove > such limitation, to make it behave like a real-world bus device. > >>> * Assign the DT node to the bound device in pci_find_and_bind_driver() >>> if there is a valid PCI "reg" encoding for a specific PCI device in >>> the device tree >>> * Create DM PCI test case against the DT node assignment >>> * Remove all compatible string in U-Boot's PCI device drivers: eg: >>> ehci_pci_ids[], xhci_pci_ids[], etc. IOW, all PCI device drivers >>> should only use U_BOOT_PCI_DEVICE(), aka the original U-Boot option 2 >>> * Fork a "pci-ns16550" driver to support U_BOOT_PCI_DEVICE(), as >>> currently PCI ns16550 device driver uses "compatible" string to do the >>> matching, and update crownbay.dts and galileo.dts (so far I only know >>> two boards are using PCI ns16550 serial port) >> >> I cannot test such changes, but I believe there is >> PCI_CLASS_COMMUNICATION_SERIAL and matching on that would suffice ? >> > > Maybe, but I need check the datasheet to confirm. This can be a good > start though. Note I can test the changes, and I can do the whole > bunch of such proposed design changes if you don't mind, but let's > wait for Simon's comments. All those sandbox changes can be done in parallel to this change though, right ? >>> * Make sure all DM PCI test cases are not broken >>> * Document all of the above changes in doc/driver-model/pci-info.txt >>> >>> I am not sure if I missed anything. Simon, could you also comment on it? > > Regards, > Bin > -- Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
