On Sun, Jan 17, 2021 at 3:01 PM Michael Walle <michael@xxxxxxxx> wrote: > > Hi Saravana, again ;) Hi again! :) > > > Cyclic dependencies in some firmware was one of the last remaining > > reasons fw_devlink=on couldn't be set by default. Now that cyclic > > dependencies don't block probing, set fw_devlink=on by default. > > > > Setting fw_devlink=on by default brings a bunch of benefits (currently, > > only for systems with device tree firmware): > > * Significantly cuts down deferred probes. > > * Device probe is effectively attempted in graph order. > > * Makes it much easier to load drivers as modules without having to > > worry about functional dependencies between modules (depmod is still > > needed for symbol dependencies). > > > > If this patch prevents some devices from probing, it's very likely due > > to the system having one or more device drivers that "probe"/set up a > > device (DT node with compatible property) without creating a struct > > device for it. If we hit such cases, the device drivers need to be > > fixed so that they populate struct devices and probe them like normal > > device drivers so that the driver core is aware of the devices and their > > status. See [1] for an example of such a case. > > > > [1] - https://lore.kernel.org/lkml/CAGETcx9PiX==mLxB9PO8Myyk6u2vhPVwTMsA5NkD-ywH5xhusw@xxxxxxxxxxxxxx/ > > Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx> > > This breaks (at least) probing of the PCIe controllers of my board. The > driver in question is > drivers/pci/controller/dwc/pci-layerscape.c > I've also put the maintainers of this driver on CC. Looks like it uses a > proper struct device. But it uses builtin_platform_driver_probe() and > apparently it waits for the iommu which uses module_platform_driver(). > Dunno if that will work together. Yeah, the builtin vs module doesn't matter. I've had fw_devlink work multiple times with the consumer driver being built in and the supplier actually loaded as a module. Making that work is one of the goals of fw_devlink. > The board device tree can be found here: > arch/arm64/boot/dts/freescale/fsl-ls1028a-kontron-sl28-var3-ads2.dts > > Attached is the log with enabled "probe deferral" messages enabled. I took a look at the logs. As you said, pci seems to be waiting on iommu, but it's not clear why the iommu didn't probe by then. Can you add initcall_debug=1 and enable the logs in device_link_add()? Btw, I realize one compromise on the logs is to send them as an attachment instead of inline. That way, it's still archived in the list, but I don't have to deal with log lines getting wrapped, etc. Thanks for reporting the issues. Also, could you try picking up all of these changes and giving it a shot. It's unlikely to help, but I want to rule out issues related to fixes in progress. https://lore.kernel.org/lkml/20210116011412.3211292-1-saravanak@xxxxxxxxxx/ https://lore.kernel.org/lkml/20210115210159.3090203-1-saravanak@xxxxxxxxxx/ https://lore.kernel.org/lkml/20201218210750.3455872-1-saravanak@xxxxxxxxxx/ Thanks, Saravana
