On Sat, Aug 25, 2007 at 07:55:56PM -0600, Matthew Wilcox wrote:
>
> This patch, loosely based on a patch from Robert Hancock, which was in
> turn based on a patch from Jesse Barnes, fixes a boot-time hang on my
> shiny new PC. The 'conflict' mentioned in the patch in my case happens
> to be between mmconfig and the graphics card, but it could easily be
> between any pair of devices if they are left enabled by the BIOS and
> mappen in the wrong place.
This issue has come up before:
http://www.uwsg.indiana.edu/hypermail/linux/kernel/0212.2/0232.html
and Ivan Kokshaysky suggested a very similar patch:
http://www.uwsg.indiana.edu/hypermail/linux/kernel/0212.2/0324.html
cheers,
grant
>
> Signed-off-by: Matthew Wilcox <[email protected]>
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 34b8dae..51ef450 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -180,11 +180,26 @@ static inline int is_64bit_memory(u32 mask)
> return 0;
> }
>
> +/*
> + * Sizing PCI BARs requires us to disable decoding, otherwise we may run
> + * into conflicts with other devices while trying to size the BAR. Normally
> + * this isn't a problem, but it happens on some machines normally, and can
> + * happen on others during PCI device hotplug. Don't disable BARs for host
> + * bridges, though. Some of them do silly things like disable accesses to
> + * RAM from the CPU
> + */
> static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
> {
> unsigned int pos, reg, next;
> u32 l, sz;
> struct resource *res;
> + u16 orig_cmd;
> +
> + if ((dev->class >> 8) != PCI_CLASS_BRIDGE_HOST) {
> + pci_read_config_word(dev, PCI_COMMAND, &orig_cmd);
> + pci_write_config_word(dev, PCI_COMMAND,
> + orig_cmd & ~(PCI_COMMAND_MEMORY | PCI_COMMAND_IO));
> + }
>
> for(pos=0; pos<howmany; pos = next) {
> u64 l64;
> @@ -283,6 +298,9 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
> }
> }
> }
> +
> + if ((dev->class >> 8) != PCI_CLASS_BRIDGE_HOST)
> + pci_write_config_word(dev, PCI_COMMAND, orig_cmd);
> }
>
> void __devinit pci_read_bridge_bases(struct pci_bus *child)
>
> --
> "Bill, look, we understand that you're interested in selling us this
> operating system, but compare it to ours. We can't possibly take such
> a retrograde step."
-
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