Messages in this thread | | | Date | Fri, 21 Nov 2014 10:31:10 -0700 | From | Bjorn Helgaas <> | Subject | Re: Removal of bus->msi assignment breaks MSI with stacked domains |
| |
On Fri, Nov 21, 2014 at 09:54:40AM +0800, Yijing Wang wrote: > >> Thomas, let me know if you want to do that. I suppose we could add a new > >> patch to add it back, but that would leave bisection broken for the > >> interval between c167caf8d174 and the patch that adds it back. > > > > Fortunately my irq/irqdomain branch is not immutable yet. So we have > > no problem at that point. I can rebase on your branch until tomorrow > > night. Or just rebase on mainline and we sort out the merge conflicts > > later, i.e. delegate them to Linus so his job of pulling stuff gets > > not completely boring. > > Hi Thomas, sorry for my introducing the broken. > > > > > What I'm more worried about is whether this intended change is going > > to inflict a problem on Jiangs intention to deduce the MSI irq domain > > from the device, which we really need for making DMAR work w/o going > > through loops and hoops. > > > > I have limited knowledge about the actual scope of iommu (DMAR) units > > versus device/bus/host-controllers, so I would appreciate a proper > > explanation for that from you or Jiang or both. > > In my personal opinion, if it's not necessary, we should not put stuff > into pci_dev or pci_bus. If we plan to save msi_controller in pci_bus or > pci_dev. > I have a proposal, I would be appreciated if you could give some comments. > First we refactor pci_host_bridge to make a generic > pci_host_bridge, then we could save pci domain in it to eliminate > arch specific functions. I aslo wanted to save msi_controller as > pci domain, but now Jiang refactor hierarchy irq domain, and > pci devices under the same pci host bridge may need to associate > to different msi_controllers.
I think this is getting ahead of ourselves. Let's make small steps.
We currently have the msi_controller pointer in struct pci_bus. That was there even before your series. Your series added pci_msi_controller(), and I reworked it so it looks like this:
static struct msi_controller *pci_msi_controller(struct pci_dev *dev) { struct msi_controller *msi_ctrl = dev->bus->msi;
if (msi_ctrl) return msi_ctrl;
return pcibios_msi_controller(dev); }
So now your series basically just removes the ARM add_bus() and remove_bus() methods and gets the MSI controller info from the ARM pci_sys_data struct instead of from pci_bus. Of course, that assumes that on ARM, all devices under a host bridge have the same MSI controller. That seems like an unwarranted assumption, but if you want to do it for ARM, that's fine with me.
> So I want to associate a msi_controller finding ops with generic pci_host_bridge, > then every pci device could find its msi_controller/irq_domain by a > common function > > E.g > > struct msi_controller *pci_msi_controller(struct pci_dev *pdev) > { > struct msi_controller *ctrl; > struct pci_host_bridge *host = find_pci_host_bridge(pdev->bus); > if (host && host->pci_get_msi_controller) > ctrl = pci_host_bridge->pci_get_msi_controller(struct pci_dev *pdev); > > return ctrl; > }
You can do this for ARM if you want (and your series already accomplishes the same effect, though implemented differently). But I don't think this is appropriate for the PCI core.
For anybody who is on this thread but not the original, I reworked the series slightly, see [1].
Bjorn
[1] http://lkml.kernel.org/r/20141121172018.GA6578@google.com
| |