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SubjectRe: [PATCH 3/3] x86,pci,acpi: Handle invalid _CRS
Date
On Tuesday 20 April 2010 11:35:59 pm Yinghai wrote:
>
> Don't clear root bus resource too early, until We can make sure _CRS works

Please observe English conventions like capitalizing the first word
of a sentence (and not things like "We" in the middle) and using
a period at the end.

> also restore it, if all _CRS get rejected because of conflicts
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>
> ---
> arch/x86/pci/acpi.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> Index: linux-2.6/arch/x86/pci/acpi.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/pci/acpi.c
> +++ linux-2.6/arch/x86/pci/acpi.c
> @@ -196,9 +196,6 @@ get_current_resources(struct acpi_device
> struct pci_root_info info;
> size_t size;
>
> - if (pci_use_crs)
> - pci_bus_remove_resources(bus);
> -
> info.bridge = device;
> info.bus = bus;
> info.res_num = 0;
> @@ -217,10 +214,20 @@ get_current_resources(struct acpi_device
> goto name_alloc_fail;
> sprintf(info.name, "PCI Bus %04x:%02x", domain, busnum);
>
> + /* Only clear that when _CRS works for sure*/

If you put a comment here, please at least add a space before the
closing "*/". Otherwise it looks sloppy.

> + if (pci_use_crs)
> + pci_bus_remove_resources(bus);
> +
> info.res_num = 0;
> acpi_walk_resources(device->handle, METHOD_NAME__CRS, setup_resource,
> &info);
>
> + if (pci_use_crs && !info.res_num) {
> + /* Restore default one */
> + bus->resource[0] = &ioport_resource;
> + bus->resource[1] = &iomem_resource;

This is ugly because it just repeats this code from pci_create_bus(),
and there's no indication either here or there that they are connected.

Admittedly, I think it's also sort of ugly that pci_bus_remove_resources()
exists at all -- I'd rather have some sort of hook so we could set the
bus resources correctly the first time.

Maybe you could at least add a pci_bus_set_default_resources() that
could be called both here and from pci_create_bus().

Why are you doing this patch? Did you see a machine where the host
bridge was left with no resources because of _CRS issues? If so,
this patch feels like a band-aid. I'd rather investigate the issue
directly, because that would probably be a Linux problem we could fix.

Also, if there *is* a reported problem, you should include a link to
the bugzilla or email thread.

Bjorn

> + }
> +
> return;
>
> name_alloc_fail:
>




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