On 2014/11/21 10:03, Jiang Liu wrote: > On 2014/11/21 9:46, Thomas Gleixner wrote: >> On Fri, 21 Nov 2014, Yijing Wang wrote: >>> On 2014/11/21 0:31, Marc Zyngier wrote: >>>> Bjorn, Yijing, >>>> >>>> I've just realized that patch c167caf8d174 (PCI/MSI: Remove useless >>>> bus->msi assignment) completely breaks MSI on arm64 when using the new >>>> MSI stacked domain: >>> >>> Sorry, this is my first part to refactor MSI related code, now how >>> to get pci msi_controller depends arch >>> functions(pcibios_msi_controller() or arch_setup_msi_irq()), we are >>> working on generic pci_host_bridge, after that, we could eventually >>> eliminate MSI arch functions and find pci dev 's msi controller by >>> pci_host_bridge->get_msi_controller(). >> >> The main question is why you think that pci_host_bridge is the proper >> place to store that information. >> >> On x86 we have DMAR units associated to a single device. Each DMAR >> unit is a seperate MSI irq domain. >> >> Can you guarantee that the pci_host_bridge is the right point to >> provide the association of the device to the irq domain? >> >> So the real question is: >> >> What is the association level requirement to properly identify the >> irqdomain for a specific device on any given architecture with and >> without IOMMU, interrupt redirection etc. >> >> To be honest: I don't know. >> >> My gut feeling tells me that it's at the device level, but I really >> leave that decision to the experts in that field. > Hi Thomas and Yijing, > Since we are allocating interrupts for a PCI device, it's > natural to get irqdomain from the PCI device itself. If we try to > get irqdomain from a PCI bus or host bridge like > pci_get_msi_irqdomain(bus or hostbridge), it may fail for x86 > because x86 may build per-device irqdomain theoretically. > So the preferred interface prototype is: > pci_get_msi_irqdomain(pci_dev) or > pcibios_msi_controller(pci_dev) > It's flexible enough. For architectures on which irqdomain is > associated with PCI bus or host bridge, you could get the bus > or host bridge from pci_dev. And it won't cause extra computation > because you always need to get bus or host bridge from the pci_dev. Hi Gerry, I mean we could find msi_controller by calling pci_host_bridge->pci_get_msi_irqdomain/msi_controller(struct pci_dev *pdev) to avoid arch weak function like pcibios_get_msi_controller(struct pci_dev *pdev). :) > Regards! > Gerry >> >> Thanks, >> >> tglx >> > > . > -- Thanks! Yijing -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
