From: bhelgaas@google•com (Bjorn Helgaas)
To: linux-arm-kernel@lists•infradead.org
Subject: Removal of bus->msi assignment breaks MSI with stacked domains
Date: Fri, 21 Nov 2014 10:31:10 -0700 [thread overview]
Message-ID: <20141121173110.GB6578@google.com> (raw)
In-Reply-To: <546E9B60.9070706@huawei.com>
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 at google.com
next prev parent reply other threads:[~2014-11-21 17:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-20 16:31 Removal of bus->msi assignment breaks MSI with stacked domains Marc Zyngier
2014-11-20 21:53 ` Bjorn Helgaas
2014-11-20 23:10 ` Thomas Gleixner
2014-11-20 23:30 ` Bjorn Helgaas
2014-11-21 9:33 ` Marc Zyngier
2014-11-21 1:54 ` Yijing Wang
2014-11-21 2:25 ` Jiang Liu
2014-11-21 3:46 ` Yijing Wang
2014-11-21 10:00 ` Marc Zyngier
2014-11-21 17:31 ` Bjorn Helgaas [this message]
2014-11-22 4:13 ` Yijing Wang
2014-11-21 1:22 ` Yijing Wang
2014-11-21 1:46 ` Thomas Gleixner
2014-11-21 2:03 ` Jiang Liu
2014-11-21 2:12 ` Yijing Wang
2014-11-21 2:05 ` Yijing Wang
2014-11-21 8:46 ` Lucas Stach
2014-11-21 10:29 ` Marc Zyngier
2014-11-21 10:49 ` Thomas Gleixner
2014-11-21 11:30 ` Marc Zyngier
2014-11-21 12:04 ` Yijing Wang
2014-11-21 10:11 ` Marc Zyngier
2014-11-21 11:57 ` Yijing Wang
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