On Thu, Nov 30, 2017 at 10:24:37AM +0000, Lorenzo Pieralisi wrote: > On Wed, Nov 29, 2017 at 11:01:33AM -0600, Bjorn Helgaas wrote: > > [+cc Lorenzo] > > > > On Sun, Nov 26, 2017 at 01:02:09AM +0530, Manikanta Maddireddy wrote: > > > pci_flags variable is used in inline functions in 'pci.h', Tegra PCIe > > > driver use one of these functions pci_add_flags() and includes 'pci.h'. > > > Export pci_flags to allow Tegra PCIe host controller driver to be > > > compiled as loadable kernel module. > > > > Here's the usage in tegra_pcie_probe(): > > > > pci_add_flags(PCI_REASSIGN_ALL_RSRC | PCI_REASSIGN_ALL_BUS); > > > > We've probably had this discussion before, but I don't know why Tegra > > needs PCI_REASSIGN_ALL_RSRC and PCI_REASSIGN_ALL_BUS. > > > > I would prefer to drop this usage of pci_add_flags() if possible. It > > seems to be just an arm/powerpc thing and I'm not convinced it's > > really necessary. > > It is hard to say if it is really necessary (because it depends > on firmware configuration - ie pci_scan_bridge()), that's the > problem. > > I suspect it can trigger regressions if we do not set it (since > it affects what pcibios_assign_all_busses() returns on eg arm/arm64). > > There are two things we can do: > > 1) Set it unconditionally in arch code (in a hook to be defined) > 2) We remove it on a per-host bridge basis and ask for testing > > I agree this may have trickled from host bridge to host bridge through > copy'n'paste and it is not based on any firmware assumtpion but I can't > say if it is really needed. My basic position is that if resources are not assigned correctly, the PCI core should automatically try to assign them, regardless of whether PCI_REASSIGN_ALL_RSRC or PCI_REASSIGN_ALL_BUS is set. If that doesn't work, I think there's something wrongin the PCI core and we should fix that. This might be an opportunity to try removing the use of pci_add_flags() and see what breaks. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
