Re: [Bug 41722] Clevo M5X0JE hangs in ACPI init

[Jesse Barnes]

On Sun, 8 Jan 2012 14:23:29 -0800
Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> On Sun, Jan 8, 2012 at 2:13 PM, Rogério Brito <rbrito@xxxxxxxxxx> wrote:
> >
> > It doesn't boot with a vanilla kernel. It only boots when I pass the options
> > above *and* compile the kernel with the following patch applied:
> >
> > ,----[ do_not_size_subtractive_decoding_transparent_pci_to_pci_bridges.patch ]
> > | diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> > | index 86b69f85..84543f5 100644
> > | --- a/drivers/pci/setup-bus.c
> > | +++ b/drivers/pci/setup-bus.c
> > | @@ -849,6 +849,10 @@ void __ref __pci_bus_size_bridges(struct pci_bus *bus,
> > |               break;
> > |
> > |       case PCI_CLASS_BRIDGE_PCI:
> > | +             /* don't size subtractive decoding (transparent)
> > | +              * PCI-to-PCI bridges */
> > | +             if (bus->self->transparent)
> > | +                     break;
> > |               pci_bridge_check_ranges(bus);
> > |               if (bus->self->is_hotplug_bridge) {
> > |                       additional_io_size  = pci_hotplug_io_size;
> > `----
> 
> Ahh. I'd forgotten about that particular PCI patch.
> 
> That is definitely the right thing to do, and commit 8fa5913d54f3
> ("PCI: remove transparent bridge sizing") did exactly that, but then
> we reverted it in commit 12c22d6ef299 because it caused some odd
> problems for some people.
> 
> I think we should try to re-do that "avoid sizing transparent bridges"
> commit, because it really should make it much easier to do PCI
> allocations under some very common situations (there's a *lot* of
> common intel transparent PCI bridges).
> 
> Jesse, Yinghai, Ram - should we try to just re-do that commit in this
> merge window, and see how that goes? We can always revert it again if
> it causes problems..

I don't remember what problems we hit, but if Ram and Yinghai are
willing to take a look at them we should go ahead and try again.

Thanks,
-- 
Jesse Barnes, Intel Open Source Technology Center

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